I only collect and repair certain models of black cast-iron Singers made through the 1950s, and those are all I planned to cover in this blog; but when my neighbor mentioned she had a thrift-store 237 that was giving her problems, I couldn't help but take a look. (While I solved the problem, this post will be more of a documented fix than a tutorial, as I've only performed this procedure a couple times and don't know it thoroughly enough to try to teach it yet.)
First thing that jumped out at me was the duct-tape spool pin. I don't know much about the 237 except that it's from the '60s, and my first thought was "Wow, Singer really started cutting corners." My neighbor confessed to creating the spool pin.
I started reading up on the 237 on the Yahoo
Vintage Singers group--it is a wealth of information--and found that it's actually a well-regarded zig-zag machine, the last of the all-metal interiors Singer made (although the little door that holds the rotating hook in place is plastic).
She said the machine was giving her tension problems. When I first encounter a machine, I never plug it in and start running it, not since I found a finish nail buried inside a 221, and a 201 with a mis-installed hook retaining ring. Had I plugged either of those machines in and hit the gas, I might've wrecked something. So I always eyeball the machine first.
Giving the 237 a visual once-over both inside and out, it finally hit me. Folks, you notice anything unusual about this photo?
Let me zoom in for you: