Symptoms
- One key stays down after you play it and does not spring back
- The key comes back up if you lift it with a fingernail, then sticks again
- The note may keep sounding because the damper stays lifted
- A key sits lower than its neighbours even before you play it
Likely causes
Object under the key
Coins, pens, hair clips and small toys slip between keys and land under the key or behind it, stopping it from rising.
Key jammed on the key slip or neighbour
A warped key slip or a key that has shifted sideways can catch and hold the key in the down position.
Very tight bushings
Severely swollen felt bushings in humid weather can grip the guide pin so hard that the key cannot return at all.
Broken or binding action part
A broken spring, a detached hammer flange, a broken hammer shank or a seized centre pin can stop the mechanism from resetting.
What you can safely check yourself
- 1Shine a flashlight into the gap between the stuck key and its neighbours and look for any object.
- 2Lift the front of the key gently with a fingernail and see whether it moves freely or catches at a particular point.
- 3Check whether the neighbouring keys are pushed sideways or touch the stuck key.
- 4On an upright, you can lift the lid and look at the hammer for that note: if it is hanging loose or out of line, something in the action is broken.
- 5Write down the note and when it started (after moving, a spill, a hot week) to help the technician.
What not to do
- Do not force the key up with a tool or keep pumping it hard; you can break the key or an action part.
- Do not spray any lubricant into the keys or action.
- Do not pull the action out of an upright or slide out the keyboard of a grand to fish for objects unless you have done it before.
Quick fixes vs. call a pro
You can usually handle it
- Removing a visible object between keys with a thin card
- Lowering humidity if several keys stick in summer
- Lifting the key gently to see if it frees up
Call a technician
- An object fell under the keys and cannot be reached
- The hammer is loose, crooked or not moving
- The key returns only when lifted by hand
- Several keys stuck after a spill or move
What a technician will do
A technician removes the key slip and, if needed, the key or the action, retrieves any object, and repairs or replaces the broken part, such as a hammer shank, spring or flange. Simple debris removal takes about 15-30 minutes. Repairing a broken action part usually takes 30-60 minutes and can often be done in one visit.
A piano holds about 18–20 tonnes of string tension. If a fix means opening the action, turning tuning pins or working near the strings, leave it to a technician.