Digitech PDS 8000 & 20/20 issues

[stevenrb718]

I have a Digitech PDS 8000 and a 20/20 and both are really grinding me. Neither work properly. Each have had the electrolytic capacitors changed. The 8000 had every IC swapped with a working 2000 and they're all fine. All the transistors have been tested, as have the majority of the resistors, and all the diodes. There is no effect but the LED lights. The repeat LED also lights after a couple seconds and stays locked on. Occasionally a loud digital squeal will occur that goes away in bypass, or when adjusting one of the trims. The 20/20 semi-works but the effects have some weird pitch-shifting phase to them rather than echo/chorus/etc. I have also swapped the majority of the ICs and checked many other components. Randomly probing several pins shows waves that are pulsing horizontally like an accordion. These 2 have been killing me and I don't know where to turn next. Help!

[The Dude]

Schematic(s) would help.

[stevenrb718]

Schematic(s) would help.

Good point lol. Unfortunately, they haven't helped me yet. The 8000 is really tough to read, but the 2000 is similar. I really have no idea what I'm missing, especially on the 8000.