The service switch isn't a problem. There is a switch on the control itself in the cabinet to turn it off. It basically turns the service menu off. I usually tell people to leave it on so you don't have to open the panel every time you need to look at the service screen.
System Fails in the 55-58 range can get ugly. They are usually caused by a noise problem, or something is shorting out putting voltage to ground.
I would start with the wiring on the tool changer arm just to make sure its not grounding out.
Does it do this when you operate the T/C manually?