My 20 year old Bernina is still going strong. I do take it in once a year for a tune up and don't seriously sweat the small stuff like when the knee lift quit working. I just wait for the next tune up and get it fixed then. I've had 2 of them and always like the quality of Bernina's machines and feet.
Just like cars, the newer machines with all the features have more things to go wrong and I feel that they need more professional maintenance. I guess its just the price you pay for all the electronic features.