The Agony of Thread that Shreds

I've had my longarm since May of 2014.  Things have gone pretty well until about 5 weeks ago, when I started having trouble with the thread breaking.

I first noticed it with the "Mystic Purple Garden" quilts - I'd quilt an area roughly 1 square meter, and the thread would snap.  I's have to stop, clear up the mess on the quilt, re-thread the machine and then carefully restart, trying not to have a double-stitch mark where the restart occurred.

As you can see, it's not just snapped, but scrunched up and shredded - leaves quite a mess on the
quilt, fiddly to pick out and restart when this happens.,

After a while, the snaps were happening about about 3/4 a square meter, then 1/2 a square meter and so on.  By the time I got to Beth's Yellow Rose of Texas quilt, I was in trouble.  That quilt should have taken about 3 hours to stitch - but with the thread breaking more and more often, I actually spent about 8 hours on it - and was sweating bullets as I went because I HAD to get that one done before I left for America on Sept. 12 (I wanted to take the quilt with me so I could deliver it to Beth in person).

I pulled out the machines user manual and read through all the things that might cause this - the only one I wasn't able to rule out was the possibility that there was something in the bobbin assembly which had developed a "spur" and was catching the thread.  I was sick at heart at this idea, as would most likely mean having a service call - and possibly shipping the machine back to the manufacturer - which would mean being without the machine for weeks and weeks.

So I rang Howard, the dealer I bought it from and chatted with him.  He offered several possibilities, but I'd already ruled them out.  Finally he asked what size needle I was using.  Well.. I looked - and I've been using size 16 needles all along.  Then he asked what kind of thread:  Superior brand.  He told me he always uses 18 needs with Superior thread.

I have a few 18 needles - they came with the machine.  As he suggested, I changed the needle from 16 to 18 and well, folks.... I'm back in business.

I'm not sure what to make of it - size 16 needles for nearly 18 months and no problems until just recently.  It doesn't make sense, but there you are.