Well, I picked up the 15-90 from the Tucson Goodwill last Thursday.
After close inspection, it appeared that someone had attempted to removed the motor . . . without unplugging the machine. Some of the wires were cracked and dry rotted but the big give away was the electric cord was definitely fried. The part of the machine where the electric cord comes through the cabinet was "bubbled" also.
I used electric tape to temporarily fix the wires that didn't have insulation. I screwed the motor back onto the machine, oiled the puppy and tested it (with a different electric cord). It ran! It squeaks! I oiled again. It ran!
Next stop the bobbin. It wouldn't come out. I unscrewed some screws (I have no idea what I'm doing) and popped the bobbin out. Cleaned it up. Oiled the bobbin area and popped the bobbin back in.
Tried sewing on the machine but it's not picking up the thread. Could have something to do with the twisted up wire spring on the tension. Could have something to do with the fact I have never sewed on a 15.
It's squeaking again.
Forgot to bring the pictures to work. :-(
Now I have two garage ornaments from Tucson Goodwill.