Sticking keys is a common problem with pianos, and can happen to any of them. A sticky key is one where the note does not respond quite as it should e.g. it can be played once.
There are many causes of sticky keys
Excess moisture often causes keys and felt bushings to swell and react sluggishly or even stick. It is very important that excess moisture and moisture fluctuations be minimized as much as possible.
Common symptoms / causes and cures (upright pianos)
The note is played and the key stays down:
The note is played and the key returns but when struck again the note does not sound
1. The hammer has not returned
If the pianos have keys that stick, are they Worthless?
Saying a piano that has a sticking key is "worthless" is like saying your house is worthless if a door sticks when the humidity is up a little. Would you tear down a house because a door was sticking? Of course not. If you tossed out every piano that had a sticky key, you'd have to toss out every piano ever built.
There are many causes of sticky keys
Excess moisture often causes keys and felt bushings to swell and react sluggishly or even stick. It is very important that excess moisture and moisture fluctuations be minimized as much as possible.
Common symptoms / causes and cures (upright pianos)
The note is played and the key stays down:
- The key itself is physically stuck down
- The front of the key is fouling on the slip rail
- Slip rails is warped - shave some off or reposition it
- The front bushings are binding on the key pin
- The key pin is rusty - clean or replace
- The bushings need lubricating and / or easing
The note is played and the key returns but when struck again the note does not sound
1. The hammer has not returned
- The tape has broken - replace
- The hammer flange is stiff - lubricate or repin
- The butt spring is broken - replace
- combination of the above
- The jack (spiral spring) is broken - replace
- The jack flange is stiff lubricate / repin
- The key capstan is adjusted too high - adjust down
- The wippen flange requires lubriaction / repinning
- The front of the wippen is fouling (the frame sometimes) - shave some off (!)
- The damper spoon is corroded / caught against back of damper bottom (underdamper only) - replace damper box cloth and / or clean / replace spoon
If the pianos have keys that stick, are they Worthless?
Saying a piano that has a sticking key is "worthless" is like saying your house is worthless if a door sticks when the humidity is up a little. Would you tear down a house because a door was sticking? Of course not. If you tossed out every piano that had a sticky key, you'd have to toss out every piano ever built.
