I heard from someone that some PianoDisc systems do not interpret
a note_on_velocity_0 event as note_off, although this is a common
practice in MIDI files in order to allow 'running status' encoding.
This may be your problem, but not very likely.  If it is, I have
a script that converts velocity 0 events to note off events.

I also have a program that works to some extent to fix gaps that are
too short to repeat.  This can save a lot of editing time.  You set
a minimum period of time in milliseconds and the program tries to make
the gaps that large by moving the note off events where necessary.  
It tries to not remove or invert notes that would be shortened to less
than nothing.

I also have a program called "MIDI Virtual Keyboard" that can be used
to test the repetition of your PianoDisc.  It is available on my web
site which is http://spencerserolls.com/  You can find various programs
on the "files4download" page which is accessible from the downloads
page.  If you want to use the "Gapfixer" program, contact me for the
latest version as it may not be up to date on the web site.  The vel=0
to note off program is not on the web site.

If you have a really old PianoDisc as I do, which is before the silent
drive system, you may have sticking solenoids.  The old ones require
lubrication to work smoothly and can get gummy and need cleaning.
Only Protek lubricant should be used on them, according to PianoDisc
support.  Unfortunately they did not specify which Protek product so
I tried the center pin lube which does seem to help a lot if you have
cleaned any gunk out of the solenoids first.

Best regards,
Spencer Chase
mailto:spencer@mcn.org