This series machine does have electronics in the foot control. Electronics started creeping in on the 830 Record with the 830E. Any mechanical machine after that is mechanical, but does have the electronic foot control that does go out. I've had to replace lots of capacitors in my Bernina machines. It may be that. If so, I would suspect your dealer will try to get you to buy a new foot control. The old ones can be repaired, so please don't chuck it! I don't know many dealers or techs that will offer to repair them, they DO want you to buy a new one.
Some of them do have a fuse, I've never worked on this model so I wouldn't be able to confirm that.