I got stranded at work today because the starter clutch arms would not catch and spin the engine. After the pedal of shame home, I took the clutch bell off, cleaned and sanded the friction surface and the shoes, reassembled and no difference. I did this routine twice to make sure. The engine will catch very intermittently, but nowhere near enough to start.
I put the drill on, spun it up, and got it started. Took it around the block, came back, and turned it off. I tried to pedal start again, and the engine turned over much easier and fired right up.
I don't know if it's the bell, or the arms, or what, but I ordered a new clutch bell and arms today. My clutch bell has a fair amount of pitting from rust, and the material on the arms is pretty thin. I hope this does it. Carrying a drill around isn't appealing.