Discussion about the Korg PolySix synthesizer

hi there -i've been having problems with my polysix lately.  but 
first a bit of background:

i bought the thing a little over a year ago (after my first 2 died, 
that's right, this is my third polysix) off of ebay from minimi123 -a 
very respectable and well-known ebay synth seller.  he had 
already changed the 
original NiCad internal battery, and it looks like he got to it
before 
any leakage occurred.  the inside is completely clean!  no 
corrosion.

anyway, the other day i turnd it on, and the "bank 4" and "program 
4" buttons stayed lit.  while these buttons stayed lit, the synth 
performd erratically, at about half volume, and i couldn't recall 
any of my stored patches.  every once in a while the lights would 
flicker out, then on again -and while the lights were off, the synth 
performed perfectly.  to me it seems like there may be some 
problem in the tape storage department -since the bank for key 
doubles as the "tape error" key in tape enable mode.  but i may 
be way off.  all i know is that i cleaned all the insides, dusted 
them, and it still is acting funny.

any recommendations?  i'd like to try to fix it myself, if i could 
figure out what was wrong with it.  but if not, does anyone know 
of a reliable repair guy?  doesn't matter where, i'll ship to just 
about anywhere (i'm in pittsburgh).  email me at 
steve@zombi.us.

peace,
steve