[lincpimp]

Your slipper setting is too loose. The problem is that when it slips it heats up and it the center goes out of round. when that happens the gear mesh is altered and the teeth strip. Put all 12 pegs in the new spur and tighten up the nut almost all the way. I usually back it off about 1/4 turn from full tight and test lightly to see if I need any more. I would also say to replace the nut every couple of times you remove it as the nylon portion does wear out.