Was getting random resets on Viper and sometimes the DMD would turn off. Removed the 5v connector from the DMD and game played fine blind with no resets. Sometimes reconnecting the 5v would cause the game to lock up. Well documented problem in the repair guides and replacing BR21 solved the problem. Glad I try to buy extra parts when placing orders because I had several bridge rectifiers on hand from when I replaced one in Baywatch.
Just posting this for future reference if anyone searches for the same problem.
On another note, I had red and blue LED 12v bars I bought for $3 each at Ollie's for another project. I always try to get a little creative with pins and these fit perfectly on top of the blacklight covers. They are not really bright, so they don't get in the way of seeing any action and they also don't interfere with the blacklight. Since I had the left ramp lit with red LEDs and right right ramp blue, it made sense to add these. Looks sharp and I can turn them on/off by opening the coin door and pressing a button.