Many years ago my ex husband's grandmother gave me an Elna Supermatic. It was also missing the lower extension of the knee controller. I improvised and used a very sturdy wire coat hanger as a replacement. It was not pretty but it worked. If you dig deep in your closet you may find a vintage one, LOL. Yes, they don't even make coat hangers like they used to. All are plastic now.
As for the motor, wish I could help. If it were mine I would try to wipe as much of the oil off of it as I could before testing it. It will likely smoke a bit. Won't hurt to try once you get a power cord.