Vehicle report
Technical service bulletins are instructions a manufacturer sent its dealers about a known fault. They are not recalls and the work is usually not free, but they are the clearest signal of a problem the manufacturer already knows about.
TB-10-007
THOR MOTOR COACH: ENGINE BRAKE SWITCH LOCATED IN THE DRIVER SIDE CONSOLE IS INCORRECT, AND ONLY ALLOWS HI ENGINE BRAKE OPERATION. THE CURRENT SWITCH INSTALLED UTILIZES THE SAME HARNESS PLUG FROM FREIGHTLINER. *PE
Complaint counts are reports filed with NHTSA, not failure rates. A common model collects more of them than a rare one that breaks more often.