First order of business was getting all three lights into an operational state again. 2 of the lights arrived with broken mirrors (one of them had the mirror assembly completely smashed - see photos).
After rebuilding the mirror assembly with epoxy, I noticed several of the stepper motors in one of the units were completely locked up. Inspection of the bearings showed those were still good, so I decided to dig deeper. Upon opening the stepper motors, I discovered the rotors were completely covered in ferrous dust (no idea). Thankfully, this was easily fixed with a compressed air gun. I believe more of the steppers will have the same ferrous dust so I'll probably end up disassembling most of them to clean them out.