I have a Janome 4800 and it's always had this problem to some extent -I can't use thicker threads, such as King Tut, and even with others it will throw an occasional wobbly. But this evening I'm really perplexed. I've hardly used the machine since it was serviced in September - and I watched the guy clean the discs - until last night, when it ran very sweetly while I did some piecing, using Masterpiece thread. Now this evening the thread is jamming in the discs as soon as I lower the presser foot. I've rethreaded it several times, but am at a loss as to what else to try - it can't need cleaning, and this has happened so suddenly, for no obvious reason.
Maybe it's just because I've made the mistake of combining this rather jinxed machine with the most jinxed quilt I've ever struggled to make!
Would be glad of any advice.