steihy

I guess Tammi got all the problems she needs for this session, but this thread (sic) in itself has turned out to be a great tension tutorial. Let's keep it up.
I know that I fiddled about a lot, but didn't really make progress until I understood the stitch forming process. It's easier to relate to the different problems and suggested solutions once you understand why there needs to be tension to snug up the stitch in the first place. Every machine manual has the usual graphics of the under-, over- or balanced stitch, but they don't really explain what's going on. Nor do they explain the need for all the big movements and the big loops in the upper thread path. What goes on under the hood is simply magic, but once you understand it the fear of working on it disappears.
Showing an animation or good pictures, would be a good start. That's also a good opportunity to show that, allthough the needle thread takes abuse and does all the work in the making, the upper and lower threads form identical parts from there on, and share the load equally for the rest of the (balanced) seam's life.

Well, maybe not that critical in quilts, I don't know. I keep forgetting that this a quilting forum, and I'm only in it for the machines.

On the more specific level: Anything that happens every once in a while, or at the odd stitch, is not a tension adjustment issue.
It has been discussed, and I agree, that spool yanking is underrated as a problem. Upstream of several friction points and disks, it takes very little force change on the spool to create significant changes at the needle, enough to tighten up the loop and miss the hook I guess. Although there are solutions as discussed, I think the modern way with the fixed, horizontal spool is an improvement. You can find this solution on some pretty old industrials, so it's not complete heresy.
I don't know if snags and stutters are as critical down below, but I am Catholic about bobbin condition. Every time I load one in the casing, I test for tension and evenness by pulling thread slowly off the bobbin, and feeling it. Unless the thread is full of knots it should come off in a completely even and smooth manner, no jerks or ticks. I guess different contact areas for different systems - horisontal of vertical - but burrs and nicks, dents and warps, will affect the action. I know some people are fairly religious about bobbin pedigree, and I don't know enough to argue, but personally I don't feel bad about replacing a tired metal one with a fresh plastic substitute. You don't have to worry about a plastic one being slightly warped - it's good or broken. I know for a fact that my 201 behaves much better after I replaced the original bobbins that came with it.

Good luck, Tammi

PS: Now I see that Miriam said most of this already, not needing so many words. Oh, well.