Recycler II 20438: shearing off nubs on main drive pulley

I replaced the blade brake on the Recycler II. I am having trouble getting the brake/flywheel assembly put back on the mower with shearing off the nubs that are on the pulley that attaches to the spindle and between the mower deck and the flywheel. If I tighten the nut real tight, I can't pull the starter rope. If I get it too loose, the flywheel shears the nubs off of the pulley. I have done that twice now, and am on my third pulley. The guy at the parts place asked a mech in the back, he said there is no trick. He said sometimes the holes in the flywheel get worn out and there is too much play, thus causing the shear. I am not sure that is right, because it seems it would have sheared off by now on its own instead of now on reassembly.



What am I doing wrong?