I cut them off, see the post. Nothing left. Mine was missing wheel cogs as well. Probably the gearbox was faulty.. Maybe yours is the same... That's why people take the cogs out... speedy
........................Keep your blades sharp......................
If the gearbox is ok then I'm guessing the PO pulled the gears out for the same reason I'm having problems with the one I have, easy to push forward no problems, but just about impossible to pull it backwards, with or without the motor running.