What was found
AFTER LEVELING AT FL350 MASTER CAUTION W/OVERHEAD ON THE MASTER CAUTION PANEL ILL. PASS. O2 LIGHT ON THEOVERHEAD WASILL. CABIN ALT. WAS AT 15,000FEET. FA CONFIRMED MASKS HAD DROPPED. AUTO FAIL LIGHT WAS ILL. BUT NO ALT. ALERT HORN HADSOUNDED. ALT. CONT. WAS SWITCHED TO STBY BUT CABIN CONTROL WAS NOT REGAINED UNTIL DECENDING THROUGH 20,000 FEET. PRESS.CONTROLLER DID NOT SWITCH FROM AUTO TO STBY AUTOMATICALLY. CORR. ACTN. RPLD. CABIN PRESSURE SWITH.PERFORMED CABIN ALT. WARNING SW.TEST. FOUND RUBBER BOOT LEAKING ON AFT SIDE OF P-DOME ON LOWER LT. SIDE. RPLD. SAME. LEAK CK. GOOD.