[ToddF]

No matter what motor you end up using, the first thing you can do to help yourselves is to add a spring to counter balance the weight of your arm. This could be as simple as a piece of surgical tubing wrapped around a pulley that's attached to your arm pivot axis. Attach the other end of the surgical tubing to your frame so that the weight of the arm is supported by the stretched tubing, not your motor. Then, the motor just has to handle arm motion, not carry the weight.

Properly counterbalanced, a window motor just MIGHT work. But, the teams at our last FRC summit concluded that window motors are supplied as object lessons for rookie teams to learn what NOT to use. Most of us just throw them in the trash. With their limited capabilities, there are much better options available. Not to mention that the thermal cutoff will kick in at the most inopportune moment, leaving you motionless until the motor cools down.