[sanddrag]

Additionally, you can set the "brake" jumper on the victor speed control, which will slow the rate of descent of your arm a little bit. However, if true non-backdrivability is what you want, a traditional way of achieving that is with a worm gear, like this. The Fisher Price motor (by itself) is a very high RPM motor though, and you'd probably want an additional stage of gearing in there somewhere. Also check out the FIRST mechanism library