Just a comment about top tension. Pulled out my 99K a little while ago, the one I did the pictorial about. Wanted to do some piecing with the ability to reverse tack my seams. I had fits. Birds nests in the bobbin area, sloppy stitches, and the feed dogs kept grabbing at my material and wadding it up. Or, I thought so.
I worked with it cranking in more and more top tension until it was up to 6 on the dial. This with #50 thread. Not right thinks I. So at one point I sat there glaring at it until I had a thought. I lowered the presser foot and turned the dial down to 3. No tension at all. Matter of fact the tension disks were floppy loose.
So I pushed in the numbered part and turned in the chrome nob until I felt some tension as I pulled the thread through the disks, then tried it. Much better. Another number or two in with the nob and then a readjust and now she's sewing better. No birds nests, the stitches have evened out, and the feed dogs seem to have quit wadding up my material. I'm pretty sure the wadding up was the loose top tension or rather the tighter bottom tension pulling on the material.
I tested it fast, slow, in between. 6 stitches per inch to 30 stitches per inch. I think I got it.
At least I hope I do.
Now I'm wondering how the tension adjuster got so messed up. I don't remember taking it apart at all.
Ah the joys of toys.
Joe