I just had a preventable "you stupid moron" moment ....
I traded into a 2001 or so vintage Singer 3810. ( I know it's not vintage, but the moral of the story applies to vintage machines too. ) It is of course a plastic covered aluminum bodied, plastic geared machine, but it sews really nice.
The spool pin was broken off so I took the machine's plastic cover off then printed out the parts book and owners manual from the Singer site. So far so good.
Went to the LSMG today and low and behold he had the parts. Yipppeeee! Got home and put it back together very carefully. No screws left over, nothing out of alinement. It even ran.
Threaded it up, put in a bobbin and pulled up the thread, so far so good.
Then when I started to sew ..... BANG!!!!! Scared the peewaddins out of me. I had one heck of time getting the machine jam that resulted cleared.
I had put the bobbin carrier, which is plastic, in just a hair off and it didn't lock. When I stared to sew it rotated around and the needle caught it and snapped off. The bobbin carrier was tilted and the whole shebang jammed.
I got it cleared and replaced the bobbin carrier correctly, threaded it up, and the thread snarled up. Over and over and over I undid snarled up wads of thread. I had the bobbin carrier out a dozen times. Other than the preexisting broken corner* and the new needle mark just made there was no obvious damage or problems with it. My frustration level was increasing 10 fold and I dropped a bunch of things. After picking them up I sat back and just stared at the machine. Thinking all sorts of bad things about it.
Then my eyes fell upon the thread take up lever. It's down inside the machine body and you can't really see if it's threaded or not. It was threaded before the jam, but now? I leaned in and looked real close, then picked up the thread from the spool end and slowly pulled it out. Nope, the thread was not through the take up lever. NUTS!!
I re-threaded the machine from top to bottom and all was well again.
The moral of this story is: If your machine was sewing properly and suddenly isn't sewing properly, RE-THREAD IT from the spool down. I felt like a total stupid moron.
Now my worries is that I may have thrown it out of time with that jam. I sure hope not. It sews straight and ZZ and some of the fancy stitches, so I'm hoping for the best.
* The bobbin carrier has been miss-seated before and the same kind of jam has broken the hook on the right corner off.
My LSMG has a new one, but it was $15.00 and I didn't have that much today. It will be replaced soon.
Don't forget ..... when in doubt, RE-THREAD IT.