I've resolved my problem, but thought I would pass the information along for someone else's use. My super z blade clutch wouldn't always come on when I engaged the switch. Several on and off attempts usually coupled with lowering the engine speed would result in the clutch engaging. Eventually it just quit working. What I discovered is my charging system wasn't working properly. I had enough to start the mower, but it wasn't enough to consistently engage the clutch while running....
2005 Hustler Super Z Blade clutch problem
2005 Hustler Super Z Blade clutch problem