Sewnoma

This was my thought - I've had this happen too. Just a tiny bit of thread lodged in my bobbin case; I think it was letting the bobbin thread sort of jump out of its groove now and then and giving me all sorts of weird and inconsistent stitch problems. (Mine is a Janome)

I hope you can figure it out!! Nothing worse than when something is broken but mysteriously fixes itself for the repair guy.

fayeberry

I have this same machine, believe it had this ping thing once or twice - I have found a small piece of thread lodged in the bobbin area. if you figure out what the issue is please let us know. My machine also sometimes mysteriously cuts the thread when I don't want it cut! I turned the foot pedal around so as not to accidentally rock back on it, but ?? it still happens, fortunately not too often.
I doubt this is your problem, but if I have a bobbin that hasn't wound evenly, my machine doesn't like it.
Good luck!

ccthomas

Are you using the same thread as the dealer?

IBQUILTIN

I would suggest that you take it down and clean the dickens out of it. If your tension is adjusted right, and you are threaded right, sometimes there is just a tiny piece of lint that you missed and it can wreck havoc with your stitches. Hope this helps

mustangquilts

I had that problem with my new Juki when I was using Bottom line thread. I took off the foam pad under the thread holder and it stopped. Its only when I use the bottom line cones. Have had no problems since.