An incident occurred where the traveling block bumped the crown on a drilling rig. The Crown-A-Matic was properly set and working at the time of the incident. An investigation revealed that the “quick-release” valve on the drum-clutch had not been cleaned for some time and was releasing the air from the drum-clutch so slowly that the clutch was dragging and caused the block to continue traveling up to the crown. It was also revealed that there was no “bumper-seal” installed at the crown at the time of this incident. No injuries and no serious equipment damage resulted from this incident but it was truly a “near-miss”.