The 3 position safety first came out in the late 1880's when trap shooting was popular. It was put on Syracuse L.C. Smith's because some shooters forgot to push the safety off when the bird was called for and therefore lost a bird. Back then many of these shoots were for prizes including money and losing a bird because of this, L.C. Smith made the 3 position safety. On a 2 position safety, when the gun is opened the safety returns to SAFE. On a 3 position safety, when the gun is opened it does not return to SAFE, it has to be manually pushed to the middle positon.
From reading your firends dilema, Richard explained how the safety works and I agree, cleaning is not the plroblem. There is a groove that the safety slide rides in, it is slightly curved and these is a larger knob on the end that fits next to the top lever that has a notch in it to catch the safety slide when the top lever is pushed to open the gun and pushes the safety slide to SAFE.
My guess is that the safety spring with the detents in it is bent or broken or something wrong with the safety slide.
