Mickey2

A lot going on here. You should not have any puckering, it can be related to tension or I'm thinking fabric feed.

There are a few things related to needle size; one is matching the eye to the thread, it has to run through easily. Another is getting a thick enough needle for the fabric; sturdy and stiff enough not to bend, and with a large enough groove on the side to accomodate for the thread. That's why upping a size or three for heavier fabrics often helps, similarly with very densely woven fabrics.

When adjusting tension, go for a medium to ligth thread weight (sew-all); I'm not sure what your Gütermann cotton might be, I guess they have selection of them. If you stick to quilting and one particular thread on this machine use it. Use two layers of cotton material for test sewing and adjusting and later on go from there. Set the tension between four and five, and if you still have loops on top, tighten bobbin tension. Make sure the thread is in the spring, and yes messing with a brush or smomthing in the bobbin area can upset the bobbin thread, even though the bobbin case in model 15 is more stable than drop in bobbin cases.

You can over oil, but it will only result in a wipe up job later on. When it's been a while since I've jused a machine I usually give it a second round oiling. These machine have decades of history, and if there's any stickyness or slow turning parts it needs repated oiling the next few days. You can give the screws in the throat plate a drop of oil now and then too, they will eventually free up. There are clever screwdrivers to better access the area under the arm, it helps a lot when you can get a 90 degree angle (straight down on the screw). There's similar bit sets available too, you might have one in the tool box already.

Regarding the bobbin tension, there are tension gauges for this. You can get by fine with out one. There is a clever lady with a blog called Archaic Arcane, she has a few videos on how to get the tension right. One of the tricks is to weigh up a bag of beans or rice, and use it as a tension gauge. It helps a lot when the thread is out of the medium sew-all weight range.

Jo Anne B.

DH was able to get the plate off, there was a loose piece of thread present under the plate, got the feed dogs cleaned better with a Q-tip, changed the needle to a 75/11 since now working with thin Walmart muslin. Switched to Aurifil thread with both top and bottom threads. Stitch length is 10 and accurate.
The forward stitches continue to be great, probably the best I have seen with this machine.
The reverse stitches are not locking, the looping and puckering is gone.
The other area of concern maybe is the upper tension dial does not turn as easily as it could, not a real problem unless this is an indicator that of what is troubling the reverse stitches.
getting closer but no cigars yet!
Thanks for all the awesome help I have received here, I have learned lots the past few days!

Mickey2

Turning reasonably smooth is enough for the tensioner, as long as it turns from about 0 at the outer limit and closer to 9 on the most inner setting. They usually don't go spot on 0 to 9, nearly so is as good as it gets. If they are wrongly adjusted they will stop half way, turn from 0 to 5, or 5 to 9, and not a full turn. I don't think this is the problem with the revers stitch.

Do you mean no locking or not loops on reverse stitching at the moment? Double check you have the maual for 15-91. It treads from right to left, and the needle goes in with the flat side to the left. Model 15 comes in various sub models and minor differences, this is one of the more significant ones. Some of them are the other way around.

Jo Anne B.

YAY!! The 15-91 reverse stitch has arrived!
I did put my stitch issues out on a Yahoo Vintage machine group.
I adjusted the bobbin tension by 180 degrees to the right, adjusted the upper tension to be straight at the 5.
All stitches look great! Even the forward stitches look better than I thought they could. If I had to be critical the reverse stitch may be a hair tight or snug, thinking this might be a good thing.
Very happy lady here, have to say the stitches look the best ever.

Mickey2- I would go back and reread your info to actually digest. Thank you for your time and tons of information.
I could not wrap my head around playing with the tensions when the forward stitch looked great.
Thank you! Your help has been invaluable, I have learned and relearned what little I knew before...lol!

Much Thanks To All !!!!