[David Brinza]

Originally Posted by Al Skierkiewicz

Guys,
There are several threads related to this issue. Window motors have a set of locking pins that seem to interact with the higher switching frequency in the Jags. Once locked, the motor has to be reversed to release the pins and allow forward motion. The rules this year allow you to remove the pins if your design does not need them. If the pins are locked and you continue to push the motor, it will over heat and the PTC will limit the current through the motor. For info on removing the pins, search window motors and John Novak. You will find a procedure for removing the pins.

We had issues with our window motors used for our arm locking up as well.

We found John Novak's post, which pointed to the previous post in the same thread by Gdeaver (Team 1640). Gdeaver provided a link to Team 1640's wiki describing the step-by-step procedure (with photos!) for removing the locking pins from the window motors. Work carefully when removing the retainer clip, as to not destroy it. That clip need to be re-installed after the pins are removed.

Our arm has worked well since removing those pins. Now the window motors are "back-drivable" and the arm "sags" when the motors are de-energized. Still, this is far better than the arm locking-up when you need to move it.