Okay, what am I doing wrong here? I've got a Bolens riding mower (Model 13AN683G163) that needs a new transmission pulley. I'm trying to remove the flange nut that holds the pulley on the transmission shaft, but every time I try to remove the nut, the shaft turns with it, causing the wheels to spin. This is about to drive me crazy! How can I stop things from turning so that the nut can be removed?

Thanks in advance!