I had the same issue with a Saturn, and it turns out that the rails needed some lithium grease applied in order to properly move.
That's what happened to me, at least. The laser couldn't complete it's movements and checks because there was too much friction and resistance on the rails it rode on. It simply couldn't move up or down to read, and I had already bought a new laser assembly for it. Put some lube and now I have a spare laser lolDo I understand correctly that the drive motor, rail, and laser focus run independently? So if one goes the others should still work? Trying to narrow things down. Took it app and and the unit looks fine. Just no life from one day to the next. I feel it's my fault, could have stressed it to the point of failure.