OutdoorKing Repair Forum Forums Restoring, Customising and Modifying Tech Talk SB Model 45 - Cutter Clutch Balance Device

I wonder if it's to do with a particular model engine being out of balance, perhaps they thought an engine vibration was the cause of the rails cracking and tyres to solve it? I say this because it is on the engine side of the clutch so has to be fixing something that is an issue even when the clutch isn't engauged