Vintage Synth Repair

Hi All,

I have a Kurzweil MicroPiano that used to play great, then one day it 
started sort of "swallowing notes" -- it's lost a bunch of voices so 
that now after maybe 10 notes it starts cutting off the first notes 
it played.

I also have several Kurzweil 1000 PX modules that I just love and use 
24/7, and am aware of their problems...which means I have pulled and 
cleaned all the ICs to get them working again, and resoldered some of 
the power joints that cracked.  They are now in good shape.

I took the MicroPiano apart a few months ago and looked around and 
didn't really see any similar issues so I cleaned it up put it back 
together, and have the same problem...nothing was fixed.

So, my question is whether anybody here is familar with the 
MicroPiano enough to know whether I can fix it or is it just not 
worth it?  I don't really need it for anything, but every once in a 
while it's useful for a remote performance of some sort or other.

Thanks!

Fred