I have the 870Q. You've gotten good advice so far but I'll add one more thing: those machines prefer a higher quality sewing thread such as Gutermann or Mettler. The only time I ever had a similar problem with mine was when it was new, and I threaded it with Coats and Clark-- birds nest disaster! A quick call to the dealer and a change to better thread solved the problem. It's a fantastic machine.

1. I think the dealer...it's sort of a crapshoot who you get on the phone - I think most of them are Janome users, and I just didn't get a Husqvarna user on the phone? I don't know. I came from using a Janome to this one, so I've got a learning curve too!

2. And good point to the thread. I was tinkering with the manufacturer's loaded thread in, but will change to Gutermann asap. I haven't tried Mettler.