My RZT 50 turns blades on when levers are pulled back instead of shutting of and shuts off when in forward position ? could it be a switch is bad if yes what switch?

Sounds like someone has been working on the wiring, probably trying to bypass the reverse cut out switches . If you follow your steer control lever down under the plastic console covers there will be a switch, one on each steer lever by where it hinges. I don't think the switch is bad because it would not work at all if it was.It is like a door bell switch, when you pull back on the steer control lever it pushes it in and disconects the circuit to the PTO switch and the blades quit until you push them forwards and lets the curent through again. Also check the push pull PTO switch .Every safety switch on the tractor will meet at that switch and plug into it, . That model cub RZT50 has to have the worst switches ever made, but they are available and cheap on ebay. Plunger Switch 430362 430 362 for Cub Cadet Troy Bilt MTD 700 Series 725... PTO Switch MTD Cub Cadet Mowers GT RZT LT Force Mowers 925 04175