What was found
REPORTED IN-FLIGHT SQUAWK, (STAB TRIM FAIL IN FLIGHT) ON AC. HSTCU WAS REMOVED AND SENT FOR TEST AND REPAIR. DURING BENCH TEST/INSPECTION THE FOLLOWING ITEMS WERE NOTED. UNIT MEMORY INDICATED (CP PITCH TRIM SWITCH JAMMED) (AC SWITCH). DURING AUTO TEST, (HSTCU DOOR SWITCH (PN 134-30901-005) FAILED) WAS INDICATED. DISASSY AND INSPECTION REVEALED SMALL AMOUNT OF CORROSION ON CIF ASSY OF HSTCU. PROBABLE CAUSES/RECOMMENDATIONS: KNOWN PROBLEM-UNRELIABLE TRIM SWITCH HAS A DOCUMENT THAT ADDRESSES THIS ISSUE. HSTCU DOOR SWITCH PROBABLY BENT AFTER INCIDENT DURING TROUBLESHOOTING, IF PRIOR TO FLIGHT FAULT WOULD HAVE BEEN INDICATED IN COCKPIT/CAUTION MECHANICS TO AVOID BENDING SWITCH ARM DURING MAINTENANCE ACTIONS.