All bearings are replaced with the proper OEM specified part numbers. Next, both stepper motors and belts are replaced, as well as all 5 of the positioning sensors.
The Harmonic Arm Drive is then rigorously tested and verified for the equivalent of processing 500 wafers without losing a step.
This not only verifies proper operation, but provides consistent wafer placement throughout the lot(s) before the tool has to re-initialize.