As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
HEADING SELECT KNOB WILL OCCASIONALLY NOT CHANGE DIGITS. MOVING OR PUSHING AND PULLING ON THE SELECTOR KNOB WILL START IT WORKING AGAIN. ACFT GROUNDED. HEADING KNOB ON MCP WAS SLIGHTLY LOOSE. TIGHTENED THE TWO SET SCREWS ON KNOB USING ALLEN WRENCH. KNOB OPS. NORMAL IAW AMM 22-11-34.