What was found
FLIGHT 6858) AFTER TAKE OFF AND DURING CLIMB RECEIVED A (STAB TRIM) AND (MACH TRIM) CAUTION, SYSTEM WOULD NOT RESET, AIRCRAFT RETURNED TO DEPARTING CITY (DSM). INTERROGATED HSTCU, NO FAULT CODES FOUND, CLEANED THE STAB TRIM PANEL AND PERFORMED AN OPERATIONAL CHECK, SYSTEM OPERATED NORMAL.