I came up with a temporary replacement for the incomplete original rear sight: In my parts box I found a complete single folding-leaf sight that was a close fit. I believe it came off an Oberndorf Mauser Model C, although I don't know if was original to that rifle. After a bit of filing and stoning (on the sight, not the rifle!) it slid into the dovetail. In general it is a sturdier sight than the original and I actually prefer the way it looks. The original sight now goes into a parts box with other spare bits from the Model S, including the guard locking screws, and the stiff trigger spring.(The original trigger pull was ridiculously heavy. I replaced it with a standard Mauser 98 trigger spring.) I also swapped out the slightly chewed up bolt stop screw. I thought there might be something special about the Wehrmann sight screw, but the standard Mauser 98 bolt stop screw fits just fine.