How To Fix Piano Keys Sticking And Why They Stick

Maintaining a piano in good condition is not complicated. Keep the piano on an inside wall to prevent temperature changes and don't move it often. Once or twice a year, have a piano tuner do some maintenance and tune the instrument, and you should be all set.

But problems do occur. Most commonly, you'll sit down to play and find a sticky key. White keys can be prone to sticking for a variety of reasons. The problem is both annoying enough to frustrate you and small enough to prevent you from immediately calling a professional.

In this guide, we're going to go through some of the things that cause sticky keys and how to solve this problem. We will start with diagnosing the problem and at the bottom of the page, we list all the possible solutions for sticky keys.

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Diagnosing A Sticky Key

The problem with diagnosing a sticky is that there could be one thing causing the problem or it could be the result of several things. Either way, follow this procedure to begin.

Start At The Front Of The Key & Check The Key Slip

To begin, start at the front of the offending key. The first thing to check is whether the white key is too close to the key slip. This will only be the case if the sticky key is white, because the black keys do not touch the key slip.

The key slip is the board that sits in front of the keys. There should be room for the key to be pressed down and then let up without ever touching or rubbing against the key slip in front of the key.

Look down in between the key and the key slip. Can you see space there? There should be several millimeters of space. If you can stick some paper or a paperclip in between the key and the key slip, then that's not the problem.

If the key is currently stuck, try gently pulling the key slip away from the key. If the key comes unstuck, then the key slip is the problem.

This usually happens if the piano is being stored in high humidity. The wood of the key slip can swell slightly, which causes the key slip to expand and press against the keys. It is also possible that the player or somebody in the house leaned too hard on the key slip and warped the key slip slightly.

Check The Key Itself

The next thing to check is the key itself. If the piano has been stored in high humidity, it is possible that the keys are swollen and are now pressing against each other. This will only happen to piano keys that are made with wood.

Take a thin, flat tip screwdriver and see if gently separating the sides of the keys free the key. If so, the key may be swollen. Be extra careful doing this to black keys, as they tend to be more fragile.

Check For Trash Or Debris

It's important to check for trash, crumbs, or other debris in the between the keys and underneath the keys. This is especially true if the piano is being played by children – I vividly remember dropping several pencils into my piano as a child and having to eventually call a piano technician.

Check between the keys with a thin, flat screwdriver, paper clip, or screwdriver. If you find an object between the keys, try to remove it, either with your tool or with a can of compressed air.

You should also check under the keys. This requires a little more work. You need to remove the lid, remove the music shelf, and remove the fallboard and fall strip – this is not as hard as it sounds, just be careful to keep the screws with the appropriate parts.

Once disassembled, look above and below the keys. Press down and lift the sticky key and see if there is anything obvious causing the problem. Paper clips, coins, pencils, food, and sheet music are all common culprits inside pianos.

Check For Corroded Rail Or Balance Pins

Diagnosing a corroded front rail pin or balance rail pin is relatively simple. You must remove the key and touch the pins. If they are smooth, then the pins are not likely to be the issue. If they are rough to the touch, they probably have a little bit of corrosion on them.

If this is the case, you can probably use metal polish to smooth and polish the pins. Once they are smooth, the key should move easily up and down on the pin. You can watch this video for a guide on polishing rail and balance pins yourself:

Checking The Jack Flange

The jack flange is a common culprit for sticky keys. The jack flange is a part of the action – the mechanism that causes a hammer to hit a string when a key is pressed. The whippen is the part of the action that sends the hammer towards the strings – the whippen has a jack and a jack spring.

If the jack spring is broken, the jack won't be able to return to its position properly. More likely, the culprit is the jack flange.

The jack flange can come unglued. Look at the action around the hammer and check all the glue. Does the sticky key look different from the others? Is the glue insufficient? If the glue joint breaks, the jack will be out of place and the key will stick.

Also common is a tight jack flange. If the note plays fine sometimes but occasionally gets stuck and won't play, it's probably a tight jack flange. The problem will usually be worse with the damper pedal down. Hold down the damper pedal and play the note over and over – see if you can get the note to stick.

The pin that holds the jack to the flange goes through a hole with felt in it. The felt can swell and cause the pin to be too tight. The same thing can happen to the whippen flange or the hammer flange.

Check The Key Bushing

One of the more common reasons for sticky keys is moisture in the key bushing. Keys are guided up and down by two metal pins that extend up from the key bed. There is also a thicker guide pin near the front of the key which keeps the key from wobbling. Both pins are lined with a thin felt bushing cloth.

When this bushing cloth becomes too moist or humid, it will swell, and this will cause the guide pins to be too tight on the keys. This can happen to brand new pianos if the humidity has changed from the show room to the house.

If you believe the key bushing is the problem, you may want to call a piano technician. They can remove the key and use a special tool to compress the felt to the appropriate depth. Sometimes, they will replace the bushing entirely, in which case they need to apply special animal hide glue and position the bushing properly.

This is a job often left to the pros, but there are tools you can use to iron the felt and do this yourself.

Fixing The Sticky Key

Fixing sticky keys on the piano

We have gone through a partial list of the things that cause sticky keys. Of course, there are other things that can go awry and cause sticky keys (broken parts, broken springs, etc.) but what I have listed above are the most common reasons for sticky keys.

Fixing a sticky key comes down to how easy the problem is to fix and your comfort level fixing it. Some problems are easy. Others require more work and knowledge.

Fixing A Swollen Key Slip

If the key slip is the problem, this is something you can probably fix yourself. Here is how to fix a swollen or warped key slip that is pressing against the keys.

Take the key slip off. There are usually screws underneath the key slip (you'll have to get under the piano and look up), which you can take out. The key slip should come off. Then, you need to make a little shim to move the key slip out and away from the keys.

You can make a shim out of a bit of cardboard or some folded up paper. Business cards work well. Place the shims on the low and high ends of the piano and then attach the key slip again. There should now be space between the slip and the keys.

Removing Junk In The Piano

If the cause is junk in the piano, you can diagnose and fix the problem at the same time. Remove the lid, remove the music shelf, and remove the fallboard and fall strip – this is not as hard as it sounds, just be careful to keep the screws with the appropriate parts.

Once disassembled, look above and below the keys. Press down and lift the sticky key and see if there is anything obvious causing the problem. Paper clips, coins, pencils, food, and sheet music are all common culprits inside pianos.

Use a knife to dislodge anything between the keys or compressed air to blow away anything underneath the keys or within the piano. If the item is large, just use your hands. You may have to get creative!

Fixing Corroded Rail Or Balance Pins

If the rail or balance pin is corroded, you need to take a metal polish to the pins and make them smooth again. To do this, you need to remove the key completely.

To remove keys, you need to remove the key slip on the piano. On upright pianos, you remove the key slip with screws attached to the bottom of the piano. Then, you need to remove the fall board, which is the board behind the keys.

There will be one more board called the retaining board that is holding the keys in across their middle section. It is usually held in place by screws at either end – if you've taken off the key slip and fall board, removing the retaining board is easy.

Then, you should be able to lift the key off the guide pins and polish the pins until they are smooth. Follow these steps in reverse order to reassemble the piano.

Fixing Swollen Felt On Bushing Or Flanges

If you have determined that the cause of the sticky key is due to swollen felt on the bushings or in a flange somewhere, this is probably time to call a piano technician. They will remove the key and use a special iron to compress and reform the felt.

Sometimes, you can free the pin by hand by moving the key laterally back and forth. To do this, you will have had to remove the key slip, fall board, and retaining board as mentioned above.

Once you lift the key, gently move it back and forth against the pin to compress the felt. The point is to compress the felt, not warp the wood, so be careful. Try three or four times and if it doesn't work, you should call a professional.

In desperate situations, you could try taking a hair-drier and blowing it laterally across the keys and key slip for a few minutes. Sometimes, this will dry out the felt and free the key.

Preventing Sticky Keys

It should be said that many of these problems can be avoided if the piano is stored and maintained properly.

If possible, the piano should be kept on an inside wall so that the temperature does not change. Large changes in temperature will cause the wood to warp over time. The piano should be moved as little as possible, both to prevent temperature change and to prevent mishaps.

You may have to install a dehumidifier in your room or piano. Ask your piano tuner about whether a dehumidifier inside the piano would work for you – this is the number one cause of sticky keys and problems with pianos, and the solution could be that simple.

Do not allow students or kids to put any liquids on your piano. Keep food away from the piano as well. Keep pencils in a jar, so they do not roll into the piano, and try to keep paper clips in a jar as well.

Taking these precautions will save you a headache in the future. If you are getting regular maintenance and treating the instrument with care, you will not have many problems.

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