As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FIRST OFFICER'S HEADING BUG DOES NOT RESPOND TO MCP HDG, FIRST OFFICER'S FLIGHT DIRECTOR DISAPPERAED ON APPROACH. GROUNDED - YES. POWER DOWN THE A/C FOR 10 MIN, POWER UP THE A/C REALIGNING IRS. PERFORMED MODE CONTROL PANEL INSTALLATION TEST IAW B737-900 AMM 22-11-34-740-801. NO FAULTS FOUND, F/O HEADING BUG RESPONSE TO MCP HEADING SELECT.