I just bought a Black Knight 2000 and everything was working without any issues. A couple days later I turn on the machine and all the audio (music, sound effects, and voice) is screeching and distorted. The lower you turn the potentiometer the more it squeals. A lot of the squealing goes away when the potentiometer is turned up, but it's still heavily distorted. It's worth noting my machine has a Rottendog 9211 MPU which was giving me some minor audio issues which are apparently normal for rottendog boards and system 11 machines. I have tried everything other forums and posts have suggested:
- New sound board to MPU ribbon cable

- New 1458 op amps on sound board
- Audio board recapped
- All voltages are normal and stable
- New TDA 2003 amps
- All boards are tightly screwed to the back panel, no missing screws
-Verified all the roms on the sound board and the MPU
-Brand new FF speakers. These were installed before the audio screeching. I re-installed the originals to see if it was my speakers but the results were the same.

And nothing has made a slight difference. The audio is so bad its unplayable which is a bummer since this was a grail for me. If anyone can give me some leads on how to fix this please let me know!

I completely forgot to update this post after figuring it out. The issue was a pinched speaker wire behind the MPU. I was able to help tsj9197 figure out they had the same exact issue.

For everyone else having this issue, check your wires!