I wouldn't mess with trying to fix the Touch &Throw 758, they are a royal pain; the wind-in place bobbin winders tend to fail and there's no replacement parts for them.
Be nice to yourself and get a vintage Singer machine no newer than the 1960s that doesn't have plastic gears. The older Berninas no older than the early 1990s are great machines, I have had mine since 1992, also a 930(2), they're a bit heavy to tote; don't give attitude. There are other brands of vintage machines that are also very good, the old Elnas if not used in years can have a flat spot on the pulley that makes the machine not sew well.
The older machines are so much better than the plastic junk sold today.
I used to sell new Singers, they are total garbage. The new Vikings are better, the Emerald line of machines are great; especially the 116 & 118.
Sharon W