What was found
DURING CLIMBOUT APPROXIMATELY 30 MINUTES INTO THE FLIGHT, THE CABIN DOOR WARNING LIGHT CAME ON. CREW FOLLOWED CHECKLIST PROCEDURES & RETURNED TO STATION. DISCREPANCY WAS INITIALLY DEFERRED IAW MEL 52-1 AFTER IT WAS DETERMINED THAT THE INDICATION SYSTEM WAS IN NEED OF ADJUSTMENT. DMI WAS CLEARED BY ADJUSTING THE DOOR AJAR SWITCH ACTUATOR. THE SWITCH IS ACTUATED BY CONTACT WITH THE CABIN INTERIOR TRIM WHEN THE DOOR IS CLOSED. THE PLASTIC TRIM WEARS FROM CONTACT WITH THE ROLLER ON THE SWITCH ACTUATOR, CAUSING NEED FOR ADJUSTMENT. THE SWITCH & ACTUATOR IS LOCATED BELOW THE BOTTOM DOOR STEP & WEAR IS ACCELERATED DURING WINTER MONTHS BY GLYCOL, SLUSH & RAMP DEBRIS THAT ENDS UP ON THE ROLLER.