As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
MCP IAS/MACH BOX HAS WHITE DOT ON AT ALL TIMES. GROUNDED - YES. REMOVED AND REPLACED DFCS MODE CONTROL PANEL IAW B737-900 AMM 22-11-34/401. JTHACH 31086 03/27/2021 ACCOMPLISHED DFCS LRU REPLACEMENT TEST FOR MCP REF AMM 22-11-34/501. ALL TESTS PASSED. ACCOMPLISHED LAND VERIFY TEST REF AMM 22-11-00/201. ALL TESTS PASSED. ALL GROUND VERIFICATION GOOD - ALL PLACARDS REMOVED.