What was found
AT FL33.0 CABIN RATE OF CLIMB WAS 50 FPM UP INDICATED CABIN ALTITUDE REACHED 9000 FT ACCOMPANIED BY ALT WARNING HORN. DESCENT INITIATED TO FL 29.0. ACFT WILL NOT HOLD PRESSURIZATION AT FL 33.0. FOUND DEBRIS IN C-PIT DOOR SEAL, REMOVED DEBRIS, PRESSURIZED AIRCRAFT, OPS CKS GOOD IAW DC8 FLOW CONTROL MANUAL.