Timing problem, Singer 6234

[Steve2]

Looking over the troubleshooting guides to sewing machines, it’s a wonder the thing ever works at all. So many moving parts have to work just right together.

Our 20-year-old Singer 6234 was in the shop a few months ago for a gear that had stripped. The gear was replaced, and because we moved to another state not long afterwards, my wife didn’t use the machine except for a quick test when it came back from the shop.

Yesterday she’s making blanket covers from sheets. No problem for a while. Some knocking noise, she said, but it worked.

Then she needed to rethread the bobbin. Didn’t work. Trying to figure out why, I saw something disturbing: the needle was hitting the rotating housing that the bobbin sits in. (Sorry I don’t know the housing’s right name.)

To be more clear, the needle goes up and down as the housing turns round and round. Part of the housing is cut away, and that’s when the needle goes down below the level of the housing.

But the timing is off, because the needle hits the housing about a quarter-inch before the cut-away starts. (How my wife ever sewed anything is beyond me.) I can slowly rotate the hand wheel to see it clearly happening.

Taking off the covers, I saw there’s a gear beneath the rotating housing. I figured if I could move the gear over a tooth, the problem would be fixed. But even after loosening the allen screw, the gear won’t budge.

Should I try reseating the toothed belt instead? But won’t that throw off the timing of everything else? (Oh yes, I've ensured the needle is all the way up.)

I don’t want to discard an otherwise usable machine, even if it’s almost 25 years old, especially as it’s used mostly for occasional mending. The cost of shop repairs argues for buying a new one. Hope you can guide me toward fixing this one.

Thanks.

[Shadeladie]

Hi and welcome to the forum!
First, I have to say that it's only the old machines that have any worth and are worth fixing. The new ones are pretty much considered disposables and not worth fixing. I would pay to have it repaired before I threw away my money on a new one. I have 7 machines, and they're all from the 40's, 50's, 60's and 70's.
If it is the timing, it may be best left to a professional, but if you think you can DIY, I'll post a link with instructions.
First, have you oiled it and put a new needle in? The needle could be bent or not be pushed up far enough. A knocking noise is never normal. Is the bobbin in correctly and have you tried rethreading the machine? If the bobbin isn't seated right, could be the problem. Even a piece of thread that got stuck in there (the housing assembly) could cause your problem.
I'm only asking because sometimes it's somthing simple and those things should be checked first.
If it's none of those things then here's the instructions (you'll need adobe reader):
http://www.tandtrepair.com/6233freefiles/HookTiming.pdf

Good luck!