Generally speaking, there's really nothing to "tune up" on a vintage machine. Given your 237 has had light usage and little to no maintenance, it probably just needs a good oiling and greasing and replacement of the belt and bobbin tire. It's unlikely there is anything out of sorts with it. Those items are not expensive.
I'd try that and see what happens. You can't ruin anything doing those chores. If it sews well, you are home free and have little invested. If it doesn't work, you can always get it serviced.
In my area, you can get good service on vintage machines, but the minimum charge is usually around $100.00. A machine you purchase for $100. will not last as long as your vintage machine. Electronics deteriorate.
bkay
Last edited by bkay; 06-27-2020 at 05:42 AM.
Reason: grammar