[jhautz]

If the screw hole hole on your plastic pinion is worn out you could try drilling another hole in the pinion smaller than the grub screw and just force threading the screw into the new hole. Being plastic the screw should just form its own threads. Although in the long run you probably should look ionto getting a metal pinion. Plastic isnt going to hold up to long. Even the aluminum pinions dont last very long.

EDIT: Just read your most recent post. Same still goes for the new hole idea though.