As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
A AUTOPILOT WOULD NEVER ENGAGE B A/P WOULD ENGAGE FOR A SECOND AND FAIL .SYSTEM SUSPECTS FAULTY ELEVATOR AUTOPILOT PRESSURE ENGAGE BUTTONS. REPLACED ELEVATOR A/P PRESSURE SWITCH, NO HELP. REPLACED ELEVATOR POSITION SENSOR M929 CAPABILITY.OPS CKS GOOD.