You can change the lock cylinder by yourself. Of course, you still have to go to buy a good lock cylinder, quality and performance should be very good (the best use of C-class lock core). Then come back and change it yourself. There is a screw on the side of the door, remove the screw lock cylinder can be extracted, if the removal of the dowel lock cylinder can not be removed, then we must remove the door handle on the two dowels, so that the door inside and outside of the handles are removed, if the lock cylinder has a lock cylinder protection cover, if you want to remove the protection cover first. Or find a maintenance master home replacement can also be.