I have been fighting this one for going on 3 months now. I hope someone has seen this before.

I have found the car in the pit with the doors wide open, 4' above the bottom floor, at 2nd and 3rd floor. It will run for about a week with no faults then go down with this string of motion faults, no drive faults and looking back through my notes it has always been going up. It will have a 121 *45 *25 18 then immediately after it will shut down on retries in search mode 431 *45 *25 18. The 2nd digit for the profile is not constant. I have replaced the car top encoder, the roller is plumb and tight to the rail, I've cleaned the rail and wheel. I've replaced the Zap board and both vane readers and re-grounded the whole car (the ground going to the car top had never been landed in the COP.) I have tuned up the velocity scaling and replaced every relay in the controller and the aux. contractor contacts. And no matter what I do I can't recreate it, not removing VC and letting it coast or opening the arm. loop. It's getting an MSU and NTS board in the morning and I have a car top encoder assembly on order for a very slight tick in the bearing.

Thanks for any help.