I'm gonna stick my neck out and say quite frankly that I do not believe that machine is unrepairable. Matter of fact I call BS on it.
I have machines with so much use there is no decals left on the bed and they sew perfectly. That machine has so little wear on it the decals are near pristine. No way in Hades could the mechanics be worn out.
You need to take that machine to someone who wants to and knows how to fix the oldies.
Joe