Lisa,
1st, welcome to TBN.
When you say you "used it for about 4.5 hr.'s", does that mean the PTO had been engaging but now won't?
I do not know the 4310. However, as far as I know, all J.D.'s have a PTO lockout safety switch under the seat (usually a black, rubber coated vertical switch, centered under the seat). This, on the 4110, is a dual position switch. In the normal position (down), you can not engage the PTO unless sitting on the seat and, if you get off the seat with the motor running it will stop the PTO and motor. This is as it should be if you are using a peice of equipment meant to be pulled by the tractor. There is an over-ride position for the switch so that a PTO driven woodsplitter or generator, or such can be run without the operator on the seat (switch up, with a bail that flips up to cover the switch so the seat does not push it back down). [NOTE: Only the rear PTO can be engaged with the operator off the seat.]
I don't suppose you got a manual with the machine??
I hope it is just a matter of the switch. And you can get back to clearing.
Tom