Stuck key

[grisell]

I have an old piano, where one key (lower c) sometimes tends to get stuck when pressed, and has to be lifted up again.
This is very annoying. I have opened the piano and looked, but I'm no mechanic and I just can't figure out what makes it stick.
Any ideas?

[richard black]

Could be practically anything, but whatever it is, if you look hard enough, you'll find it. A small, bright flashlight is your most helpful tool here!

[faulty_damper]

Or the wood could be swollen where it puts pressure against the metal rails which causes too much friction, hence the symptom of stuckiness.

[gyzzzmo]

Maybe something between the notes, or the wooden extenders deeper in the piano (mouse poo?)

gyzzz :p

[pianodoc]

Here are some hints...

Look and see if the hammers that strike the strings are rubbing.  Pretty common in old upright pianos down in the bass where the hammers are slanted. 

When the key is stuck, see if moving the B or C# key causes the C key to move.  It is very common for "little stuff" to get jammed between the keys, causing them to bind with a neighboring key.

There are a bunch of different options, some easy to fix, some not.  You will probably have to call your piano tech to find out what's going on...

[dan101]

Give it to the tech guy and get it tuned at the same time. A patient technician will often show you what the problem is first hand, thereby satisfying your curiousity.

[daniloperusina]

Give it to the tech guy and get it tuned at the same time. A patient technician will often show you what the problem is first hand, thereby satisfying your curiousity.

I agree!
I do this kind of job from time to time, and I've given up trying to guess on the telephone! Once there was a piece of cardboard from a children's game invisible tucked down between the keys, another time I had to cut off wood from the back of the key (poor manufacturing quality!).
Thing is, the cardboard you could fix yourself, virtually everything else requires a technician's trained eye to discover the fault and come up with suitable repair in order not to damage the piano. Many such faults in the action are quite easy fixes, but you need to know what and how to do it.

[kantsuiex]

I always has this kind of experience....
Use WD40!!!  or other lubricant....
Put some on all joint so the hammer,,
In fact, the key and the system of hammer are separate..
you can take out the key and adjust the height of that screw...
also, add some WD40 on the axis under the key..

But it'd better find a techinican