As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
UPON LEVELING FL 260 LOUD PIERCING SQUEAL FROM FWD ENTRY DOOR. RAISED CABIN ALTITUDE, LOWERED CABIN ALT, CLIMBED A/C AND DESCENDED A/C. CABIN 5600 TO 1000 FT. A/C FL310 TO FL240. NO IMPROVEMENT. SQUEAL REMAINED. FOUND UPPER HINGE SEAL OUT OF PLACE. INSTALLED PIN IN HINGE FITTING, CKS OK.