Working on a Bally Black Belt. Forgive me as I don't have much experience working on 6803s. Not mine, but I have seen this pin play recently. It was out on the floor for a while and it was reported to me that either the GI or feature lights went dark. The diagnosis was unclear. It is worth noting that though I don't capture it on the video, some feature lights and some GI do light up on boot sequence. It was wrapped up before I could review any issues and then I brought it home to fix. Anyway, I fire it on, get three flashes from the sound board, nine from the MPU, which is what I am expecting for a successful boot. However, all I get is a repeating trough solenoid firing and a flashing light at the plunger. See video for MPU boot and issue.
Any thoughts? I have reseated everything, put new batteries in (they are off the board and no acid damage), and checked all the fuses.
Here is the video of boot: https://imgur.com/a/b2dXAla
Thanks so much for your help!!!