Window Motors Breaking!

[roeiy]

Hello, our robot is almost finished. As you can see, we have a lay-up robot that uses an elevator to place a magazine directly in front of the basket, then release three balls in to it. To tilt the magazine we use 2 regular window motors connected to each side of the magazine. However- we encounter a repeating problem: one of our window motors keeps breaking upon rotation. So far we have lost 3 motors to it. Another problem is the gear: The motor stalls whenever we try to lower the magazine down to a horizontal postion and we can only do it by giving it a bit of momentum.
Have you ever encountered these kind of problems before?

http://www.youtube.com/watch?v=E7UvG...ature=youtu.be

thanks.