Game has basically played and worked fine the short time since I've owned it. But now during early game play it will deteriorate into garble, low volume and "crosstalk" of tunes and speech. I get a "music failure ID 00 567 L6" message. I checked the MPU and found hand-written labels on 1 & 2 L-6 ROMS: suspect clues of replacements? Is this where I should start? I read past posting history on this failure code but could find no definitive solutions. I found a used L-6 set on ebay, but is that a good idea and will that address the issue? This newbie has no idea. Would be appreciate any advice.

I should add that the two L-6 ROM sets are U26 and U27. Also, U5 ("music and speech") would be a novice's likely suspect but that is clearly too logical for these SS logic circuits. I have not removed the sound board or MPU for visual inspection of the reverse sides.

Update: I played several games today after the machine sat idle for 36 hours. It displayed the same music failure when first turned on, but music and speech played normal for 3 games, one game of which was a new house record, so I was able to confirm normal speech and music thru all game functions. I shut down and turned it back on again. No failure message except when I performed the music test. I will run the machine thru several dozen games and leave it on for a longer Period of time if that might imply heat effects on L6 failure. Please advise. Thank you.

Thanks Ken. I removed and reseated every connector on the mpu board, and I also did the same for the connectors that go from the mpu to the sound board. Played 3 games with no issues. If the failure recurs I think I should at least try replacing u26 and u27 L6 roms on the mpu before the more radical and expensive mpu swap. Yes?

Jokerz sound board is unique to all system 11 sound boards, or so I've read in posts here. One photo shows the U6 socket empty. The other shows the MPU with the two labeled L-6 ROMs down at the bottom to which the error code refers.

I discovered something else while in the back box: the notorious Jokerz hum was louder than usual, so while it was on and in game-play mode, I rerouted the ribbon cable that runs from the display to the MPU and the hum disappeared for the first time since I've owned this machine. EMI defeated! Eureka! Maybe I should post this discovery, although I suspect others have probably figured this out. We'll see if it lasts. Good luck with Police Force. Regards and thanks.

Jokerz MPU (resized).JPG

Jokerz sound board (resized).JPG