For the SM420 I would contact someone at that Novak link Bill put up and see what they recomend. The only choices I can see to fix the loose pins, is #1 Pins with an oversized end that contacts the cast iron hole, and normal size for the shift lever retainer. #2 ream the holes larger and install bushings for the pins. #3 weld and redrill the holes. #4 Epoxy ie JB weld the pins in the holes. #5 If they aren't too loose use locktite retaining compound.
