There is a plastic gear in connection with the cam stack, the only thing you can do is check it. Lift the top up, move the stitch length lever to one of the stitch patterns, turn the hand wheel by hand and watch as it turns. Any cracks or damage show easily. The 741 has an external motor in the back, check the motor belt (possibly under a belt guard cover). I think it has an internal vertical belt connecting the parts on the under side. I'm not entirely sure on this point, since some of the flat beds are a bit different and I am more used to the freearm models. There might be a vertical turning rod of there's no belt. I think it's a slightly simpler version of the 740, with the same rotary hook and bobbin case. These are heavier and sturdier models made for more speed. In theory it should be pretty close to the machine in
this blog. It looks like the only belt on this machine is the motor belt.