As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
IAS/MACH WINDOW ON AFDS MODE CONTROL PANEL DOES NOT DIM PROPORTIONAL TO THE OTHER WINDOWS/DISPLAYS ON THE PANEL. WHEN PANEL IS DIMMED FOR NIGHT OPS USING MAIN PANEL BRIGHTNESS KNOB, IAS/MACH WINDOW APPEARS INOPERATIVE (NOT VISIBLE). GROUNDED - YES. REMOVED AND REPLACED DFCS MODE CONTROL PANEL REF AMM 22-11-34/401. PERFORMED MODE CONTROL PANEL INSTALLATION TEST SUCCESSFULLY REF AMM 22-11-34-740-801.