Watson from experience with my Gammill if you are experiencing breakage near the end of your quilt sandwich, somewhere the quilt sandwich is hanging up putting pressure on where you are sewing. Since I don't know how your setup works exactly I can't say for sure but I do know I was having breakage and after checking many things, tension, etc the problem was I needed to raise my lift bar so the underside of the quilt had more clearance. Is this as clear as mud???
On Gammills we have a 'wheel' that we can turn to raise or lower the bar that rides near the back of the throat.
Hope this helps. Other than changing the needle and rethreading and checking the bobbin this is all I can think of. Good luck.

I have a Janome with a 9 inch throat on a quilting frame. I guess calling it a short arm or "shorty" would be correct.
Are you allowing enough space from the take up bar to the machine bed? I was told to be able to just get two fingers between the take up bar and the machine bed for nice smooth stitches.

Sounds to me like one (or more) of your rails is/are bowed. When you get your quilt off, take a good metal ruler and make sure the distance between them is all the same. In other words, make sure that they are all truly parallel.
Often one side or the other seems to be off. You can address this by figuring out which side is looser, then adding a layer of batting to the quilt sandwich roll. You don't want to quilt this extra batting, just stuff it into the unquilted roll to take up the slack on the looser portion to even everything out so you have the same tension across the whole frame.

I have a long arm and always pick up some kind of new tips when subjects like this come up. If your problem is always in the same area, then really look that area over good for any inconsistencies. For me, it is much harder to fix a problem when it is intermittent. Thanks to all of you for the good advice given here.

Interestingly enough....I had an issue on one quilt where everything would be going good and then all of a sudden my thread would break and it was in almost the same spot every time. I had to get my husband to come in and run the machine slowly and then I spotted that at about 2/3rds of the way down the track, my upper thread would get loose and catch on a small jutting out piece on my long arm. I moved the spool to my other thread holder and the problem fixed itself.

Just to put a finish to this thread, it seems that the reason for my problem was that one of my encoders was loose. I tightened it up and the problem seems to have disappeared. Lets hope it stays that way!

Thanks for all the suggestions.

Watson