I've mentioned the Singer 127 I picked up a month or so back that was so incredibly filthy and gummed up with old oil, it took me a month of cleaning just to get it where I could think about test sewing with it.
Well last week I did the first test stitches and they were a disaster. Way too much top tension. There was no way I could make it sew, not even by cranking in more shuttle tension. Somewhere back in time someone had replaced the top tension beehive spring with one taller and made from thicker wire than the original. Even with the adjusting screw backed out till it was almost falling off there was so much tension the top thread just would not pass through the disks.
I took the spring out of my 66-1 and put it in the 127 which then sewed beautifully. ( Screwed up the 66 though, thought I'd never get the tension set back right ).
Yesterday I went to the LSMG and got a more proper spring. Oh what a difference. I put the machine in my test treadle and worked with it for a while. It took some time and sewing to fine tune the shuttle and top tension, but I got the machine to sew proper looking stitches with good tension now.
It's still just a well worn machine with signs of neglect and some rust pits but she'll sew nicely now. Now I need a treadle for her. No motor or hand crank, she deserves a treadle.