Pulling my hair out

If your disconnect switch is older than 5 years, it's time to replace it. It's a maintenance item that is often overlooked and should be replaced every 3-5 years. I've had a lot guys with issues with Optimas as well, even mounted in the correct orientation. Dataloggers will tell you really quick the whole story, but since you don't have one the light bulb wired in the supply to your MSD box trick will work as long as the power cycle is long enough to flicker the light. Electronics don't like fast power cycles and may be the reason the shift box went to lunch in the first place.