What was found
REPEAT WRITEUP. MAIN CABIN DOOR BEGINS TO WHISTLE AT 2.3 PSI TIL 2.0 PSI DURING EVERY DESCENT. SEE ATTACHED VIDEO. CORRECTIVE ACTION: REMOVED PRIMARY DOOR SEAL P/N 9914814-1. INSTALLED NEW PRIMARY SEAL P/N 9914814-1 W/ RETAINERS. SANDED DOWN CRACKS ON MED SMOOTH. SANDED AREA TO BE PAINTED. MASKED OFF ENTIRE AREA. MIXED PAINT AND APPLIED 4 COATS OF PAINT WITH 30MIN INTERVALS ACTUATED DOOR SEVERAL TIMES W/ NO ISSUES. PRESSURIZED USING APU TO 9.7 PSID. NO LEAKS OR ABNORMAL NOISES NOTICED WHILE PRESSURIZING OR DEPRESSURIZING. OPS & LEAK CHECKS GOOD. RETURNED AIRCRAFT TO ORIGINAL CONDITION. ALL WORK PERFORMED IAW CE-680A AMM 52-15-15, 52-10-40, 52-10-35, 21-30-00.