As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AUTO THROTTLES WONT STAY ENGAGED. GROUNDED - YES. ACCOMPLISHED T/S FOR FAULT 22-31688 PERB737-900 FIM 22-32 TASK 819 - INITIAL EVALUATION DID NOT CONFIRM FAULT. PERFORMED AUTOTHROTTLE OPERATIONAL TEST PER B737-900 AMM 22-31-00-710-801 - ALL TESTS PASS.