I love it when I have a project like this!
Done list:
Clean the petrified tape off the needle plate.
Clean bobbin hook.
Reshaped bobbin winder tension disk spring.
She's had tape on her bed for a seam guide. No biggie, I'm guilty of that minor sin myself. But this tape was looong past it's prime. Peeled the scotch tape off and found the crusty remains of what might have once, very long ago, been masking tape. Eew. Soaked the plate in soapy water to soften it enough to scrub off. Took two soaks but it's clean now.
While oiling her last night she suddenly wouldn't move through part of the stitch cycle. She'd move most of the way through, then just stop at this one section. I carefuly inspected everywhere but the bobbin hook race and stitch width adjuster because the screws stubbornly refused to move. Nothing. Since the movement didn't feel or sound crunchy (indicating hard, gear mangling crud) I figured the oiling knocked some thread into the works around the bobbin hook. The range of motion had increased as I was moving the handwheel durring the inspection so I just gently worked the handwheel back and forth until she could run through the cycle again so I could finish oiling, though she still had a hicup.
The next day (today) I got the bobbin hook screws loose and the hook and it's race were strangely clear of everything but oil and small traces of that hard-packed flat gunk machines tend to get. After I cleaned and oiled the area she still had the cycle hicup, even without the hook back in place. Then I noticed a new symptom: a quiet squeek. Squeek = not good, squeek = friction. Hunted it down to an alignment guide for the needle bar that I'd somehow missed oiling. Oil = no squeek and hicup mostly gone. Mostly. She does hesitate a bit at that same point in the cycle, at the slight pause where movement changes from moving the needle up to moving it down. That sort of problem is pretty common with machines so I think the catch in the cycle was a combination of that awkward movement change and lack of oil and/or some tiny bit of gunk in just the wrong spot.
The spring for the bobbin winder tension was bent and stuck out. It would work, but it'd also catch on something sooner or latter. The pin is pressed onto the post and doesn't come off, but the spring can be partialy pulled in front of the disks where it's easier to reshape. Squeezing the spring gently around and around to tighten the coil was a bit fiddly but only took maybe five minutes. When I put the spring back it cheerfully hid behind the disks in the no-sang-um zone.
Before, spring pulled forward
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The coil of the spring doesn't just look bigger than the disks, it was. Also note how the end is far out and loose. Far out and loose is good for a vacation but not for a tension spring.
After, spring still forward
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Coil now smaller than the disks and end overlaps with the coil, all tucked in and safe. Is it just me or does it look happier?