rehjaeger

I was given a Dremel 1680 scroll saw in non-working condition, and need some help on where to start looking for the problem. Everything seems to work, the motor runs, but the blade, which is correctly attached, moves down (one stroke) but will not reciprocate. I have a manual and parts list, and am fairly proficient at repairing things, but wanted to see if anyone could give me some ideas about what could be wrong or where to start looking. Thanks!