Cable streched on swisher trailmower

Pull the belt cover off on the side of the engage lever and you will see that it is not a wire cable that engages the idler pulley. It's a rod connected to a long spring. Perhaps the spring came off or is defective as it puts tension on the idler pulley against the drive belt when you engage the blades. Further, there is a return spring to pull the idler pulley away from the drive belt when you disengage the blades. Check all the connections for the springs and see that the engage lever is mounted tightly. Also check the idler pulley itself.