Player piano problem

[Patrick Poulson]

Jon: The first branch is the best description of the problem: the hammer 
lifts off the rail and stays off, the key stays depressed, and does not 
return. This is a Hallet and Davis player. That is the limit of my player 
knowledge. I don't know the different kinds of stacks, or primary valves. 
The roll is tracking properly. My guess is a tubing problem, or a valve 
problem.
Thanks ,
Patrick