Which Manufacturer is it? If it is Bendix then they are out of business. You would either have to rebuild with parts you might be able to find or change it out to a new one. If we ever have to replace our Bendix it would have to be
Cruise King LLC then to do it with. We did have a problem with ours that we were lucky enough to find the parts for to fix for $75 so we are good for now.