Submitted for the first time into the show the game ran for the first couple of days but by Sunday the monitor had lost sync and wouldn't adjust to sync lock :(
I pulled the chassis from the cab to test on the bench suspecting it was a monitor issue rather than a board issue. The output of TR1 (BC237) looked poor. Replacing TR1 brought back horizontal sync lock but the vertical sync lock was out of phase, "ami Kon" rather than "Konami" in the center of the screen. Swapping out the TDA2593 made no difference. Tweaking the vertical sync pot did fix the vertical sync phase lock, but the pot was very sensitive to adjustment. The pot resistance measured OK and once set it stayed locked for several hours so I decided to return it to the cabinet. Back in the cabinet the sync lock showed no issues and thus I declared the chassis fixed.