What was found
DURING CLIMB-OUT FROM MEM-DFW, AT APPROXIMATELY 9,000 FEET THE STAB TRIM AND MACH TRIM DISENGAGED. THE TRIM WOULD NOT RESET AND WAS LAST POSITIONED AT THREE DEGREES. QRH PROCEDURES WERE COMPLIED WITH AND AN EMERGENCY DECLARED. THE AIRCRAFT LANDED SAFELY IN DFW. MAINTENANCE REMOVED AND REPLACED THE CAPTAINS TRIM DISCONNECT SWITCH. OPS CHECKS GOOD. AIRCRAFT OK FOR SERVICE. (M)