A request for how to remove the back cover from a Yale lock was found in another posting. The patent for this LOBC, Locked On By Combination feature is by Emory Stockwell #299695 June 3, 1884. If the comb is unknown and you have some appreciation of lock manipulation, pressure can be applied to the sliding cover once the screw is removed. Otherwise a small hole drilled near the built in fence on the back cover will suffice. More often than not the locking tabs on the back covers have been broken off by technicians servicing the locks. This feature was widely used on many of the numerous models of Yale bronze locks starting in the 1880’s on well into the 1900’s. By the way, the model shown in the patent is the fairly rare Yale model 023-½. Doug I forgot that should you have the comb there will be an index mark low on the dial ring to dial to. These marks vary depending on offset and handing.
