As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
STAB TRIM AND MACH TRIM DISCONNECTED IN FLIGHT. FOLLOWED QRH. ABOUT 1 MINUTE LATER, DISCONNECTED AGAIN AND WOULD NOT RESET. RETURNED TO SLC AND FOLLOWED QRH.FOUND BAD TRIM SWITCH ON FO'S YOKE. R&R SWITCH IAW 27-41-05. OPS CHECK GOOD. SELF TEST OF HSTCU OPS CHECKS GOOD.