Open it up, yes indeed. You'll lose your patches, but poly 800s have increadably nasty front panel buttons. Dissasemle CAREFULLY and clean all the contacts with contact cleaner.Keyboard as well. If this does not fix the problem, It might have something to do with addresing. If I remeber right, the poly 800 has custom chips. If any go, it goes, and you're SOL- unless you find that one of the chip legs has a bad joint or a wire is off somewhere. Then, break out the iron. If it is dead past this, save the AD2609 filter and the joystick, as it is a great filter and the joystick can breath new life into damaged poly 800's and DW-8000's. Best of luck.