What was found
DURING CRUISE FLIGHT, THE CAPTAIN NOTICED THE CABIN ALTITUDE CLIMBING SLOWLY. THE CABIN ALTITUDE CLIMBED TO THE POINT OF SETTING OFF THE EMERGENCY PRESSURIZATION VALVES WHICH DROVE THE CABIN ALTITUDE DOWN. THE CREW ELECTED TO LAND AT THE NEAREST AIRPORT FOR MAINTENANCE, KSTP. FOUND FORWARD CABIN DOOR SEAL PINCHED AT THE TOP AND BOTTOM SPLIT LINE WHEN THE DOOR IS CLOSED. STRAIGHTEND FORWARD LATCH ARM TO CLEAR SEAL AND CHECKED DOOR SEAL WITH DOORS CLOSED. PERFORMED GROUND PRESSURIZATION CHECKS SATISFACTORILY. DEPARTED KSTP FOR KYIP MONITORING CABIN PRESSURE AND AIRCRAFT ALTITUDE PER MEL WITH NO DEFECTS NOTED. ALL WORK PERFORMED IAW THE LEARJET 35/36/35A/36A MM.