Welcome to the Quilting Board!
No, that wasn't it. I have no idea why it did what it did but I took the whole thing apart quite a few times looking for problems.
How are the threads on the tension assembly? It seems like the only way an "old school" tensioner would loosen off is if the threads are stripped. (possibly inside the nut instead of the post, if the post looks good?)
I have had several machines that the tension adjusting knob would loosen as I sewed with them. To cure that I'd disassemble them and spread the two fingers of the threaded shaft apart until the adjusting knob was a tight friction fit. After that they held their settings.
OH! *face palm!* You know, the last 2 machines I tuned up, I had to actually squish them a little, just to get the nuts on without cross threading them. I've had to spread them in the past too.
I should have thought about that. It's a really good possibility.
I had a tiny spot of a rustlike substance on the inside of the tension disk. It contantly unscrewed the thread tension. I took an fine nail file and then coated it with clear fingernail polish. Once put back together it works fine now.
don't stop!just keep trying and something usable will turn out!!