I was given a Model 353 from a friend, the original owner, who purchased it new in 1975. It has been in his closet since about 1980 and was never cleaned. It's was in fairly decent shape with a need for a serious cleaning. During the disassembly and cleaning I noticed that the safety lever was jury rigged onto the safety pin post with a piece of wire due to a missing safety retaining ring. My friend doesn't remember the circumstances of this. I ordered a new retaining ring from Numrich but it’s not even close to fitting correctly. The retaining ring barely clips on and it's too thin for the application. I called Numrich thinking it may be the wrong part but they don’t have a clue. According to the schematic it’s correct. I was hoping to talk to a technical expert at Numrich but that's not going to happen. I’m at wits end and was just hoping to get some help from anyone that is familiar with this model. I really appreciate any help.