MORTISE LOCK CASE HAS STRIPPED OUT CYLINDER THREADS ??? When mortise cylinders and lock cases are new they screw together without a problem. Often times a mortise cylinder is forced out of a lock without loosening the retaining screw. Other times an inexperienced person will force a mortise cylinder into a lock crooked. These actions result in stripping the threads of the cylinder or the lock case itself.The HPC Mortise Cylinder Lock Tap is designed to repair this type of damage. The Tap can easily be twisted into a stripped lock case cutting new useable threads into an otherwise ruined lock.