I have the CE200 and like oldhag said, it likes to be kept lint free :D
They are also touchy about the bobbins, they are plastic, and the machine doesn't like it if they have the slightest rough spot or burr on the edges of them.
I just check the bobbin over well before and after filling, and it seems to have cured that issue.
I use it a lot and wish that I had the CE250 because of the bigger hoop available :D:D:D