Oh boy, do I feel for you. I'm having similar experiences with my Janome (works then doesn't, goes to the shop, seems to be fixed, then acts up again). The dealer is also the servicer and they are more interested in selling than fixing, although my machine is only a bit over a year old. And the shop is about 50 miles away (each direction). Looking for a local serviceperson since the dealer charges me anyway.
I hope you're back up and running soon.