Korg DW8000, Mono/Poly, MS-20...

i just purchased another DW-8000 and it is having some serious tuning 
problems. some patches randomly sound a half-step lower or higher 
than the others... the pitch bend can't go an entire octave, it's a 
half-step flat when bent.

any ideas how to fix this?

-r. andrew scott
[www.divinemasquerade.com/synths/dw8000.htm]