Well at least you have the engine running now. However, there is still a problem. You can see the lights go out momentarily when the engine goes over the switch.
I'd look at both center rail pickups on the engine. Maybe one is non longer connected (wire broke?).
Already tested that, at least he said he did. The issue with the switches is that they are spaced to drop power briefly to the engine, the voids match up with the rollers. However, with a good battery (or BCR), the engine flywheels carry him to power again, the battery keeps the electronics humming, and the engine continues on. If a roller were not connected, the lights would have been out a lot longer and twice for the two switch gaps. Even with a good battery, I doubt a PS/2 engine would make it around all those switches with one roller.