I'm not an expert, but it kinda reminds me of my "Japanese 15" - basically a clone of a Singer 15. The screw you're referring to on the front seems to lock the stitch length in place - you can still reverse but it keeps it from getting too long. I would recommend giving it a thorough cleaning and oiling. You could remove the light and see if that's the problem... I was able to buy a replacement for the power cord (same setup as you described) and my husband re-wired it to the foot pedal. The old cord was truly old, it was not insulated at all and we didn't feel safe with using it. I'm so happy with this machine, I've been using it every chance I get for the last 2 days. (only had it 3 weeks :)