What was found
MAIN DOOR PRIMARY SEAL: AFTER LANDING, WITH APU STARTED AIRBORNE IN THE TERMINAL AREA, & STILL RUNNING IN THE CHOCKS, MAIN DOOR PRIMARY SEAL TOOK 12-15 SECS TO DEFLATE AFTER DOOR HANDLE WAS ROTATED TO OPEN POSITION, PREVENTING DOOR FROM OPENING. AFTER OWNER DEPARTED, CYCLED DOOR SEVERAL TIMES. MAIN DOOR PRIMARY SEAL DEFLATED IN 7 SECS AFTER DOOR HANDLE WAS ROTATED TO OPEN POSITION ON THE FIRST CYCLE, AND 4 SECS TO DEFLATE ON SUBSEQUENT CYCLES. POWERED UP A C AND APU PERFORMED OPS CHK OF MED SEALS OPS CHK GOOD. DECIDED TO PURGE AND INSP & CLEAN INFLATION DEFLATION VALVE. PURGED SERVICE AIR SYSTEM & CLEANED & LUBED MED SEAL DEFLATION VALVE. OPS CHK GOOD IAW AMM 52-I0-04.