Hello everyone,  Jim Perkin asks about animating his keys.  Most piano
keys have lead weights right at the back end under the piano action.
If you remove each key in turn and take out this weight, the key will
fall every time the note is activated.  This does not effect the action.

Some player pianos had key locks operated by a lever under the key bed
which pushed a bar up under the keys, presumably to stop people playing
along with the roll!  I hope this helps.

Cheers,
Rob Barker
http://www.robbarkerorgans.co.uk/