The only thing is right now it is running fine. Why call a service technician? They follow the "if it ain't broke, don't fix it" method instead of an ounce of prevention is worth a pound of cure. I repaired the wheels and guides because they let it get so bad practically all the wheels were broken and it just barely stayed up and couldn't be removed. If they would have fixed the wheels sooner the guides would not have needed the guides.
Frankly, it was ridiculous trying to get stuff in and out of the top rack.