Hi Sheldon,
While you are at it, check your other plungers by simply lifting them up and letting them fall back into their coils. If any are slow, sand them.
Bill
The solenoid plunger goes through a tube in the center of the solenoid coil. It sounds like the inside of the tube has distorted out-of-round just a bit. If I am correct on my diagnosis, correcting it is not difficult.
The action has to be pulled from the piano in order to be able to have access to the solenoid plunger that is "sticking." Unless you are comfortable removing the action, you should have a piano technician remove the action from the piano. Then pull the plunger from the solenoid coil.
Remove the rubber cap from the end of the plunger. Take a piece of 400 - 600 grit sandpaper and roll it into a tube, with the abrasive on the inside. The plunger is coated will a molybdenum dry lubricant, which is very sandable. Holding the plunger at the rod end (where the cap was) spin it inside the sandpaper tube. Pull it out and test it. (We use the sandpaper tube to make sure we keep the plunger round.) Wipe off the plunger. The plunger should fall free into the coil. If not, spin it again in the sandpaper tube and check. Continue as necessary.
While you are at it, check your other plungers by simply lifting them up and letting them fall back into their coils. If any are slow, sand them.
Bill
On Sun, Jan 19, 2014 at 7:07 PM, Sheldon H. Deluty, M.D. <mdshd@...> wrote:
Good Evening:
I have a Mark II Baby Grand with a DKC850 upgrade
The middle E (just above middle C) key now gets stuck halfway down each time it is "played" by the Disklavier (not when played manually) - I have to bring it up or it stays halfway down
What would be involved in repairing such a problem?
Thank you
Sheldon Deluty