Joe, sometimes if one or more of the stock countersunk flathead screws holding the latch mechanism in the door loosen slightly, the lock (or latch) may stop working. Those screws need to be installed with Lock-Tite and an impact driver to prevent loosening. I use a hammer-driven impact driver meant for motorcycle engine screws & bolts. And be extremely careful of that plastic ball-coupling on the lock adjusting rod. The plastic is nearly 50 yrs old and it gets brittle with age (like owners!) If the ball-socket cracks, you will be far worse off than you are now!