I am replacing the lower drive belt on my 23hp Troy-bilt pedal drive garden tractor. The last step in removing the belt is to remove the hex bolt from the center of the electric PTO clutch. When I try to loosen the hex bolt part of the electric clutch and the engine pulley turns at the same time.

What is the trick or secret in keeping these parts from turning with the hex bolt in order to loosen the bolt?

Thanks for any help.