Small Engines (Lawn Mowers, etc.): Re: STX-38, shaft seal, taking a closer look

Question
Hello, I have a John Deere STX-38 Yellow deck. Can you tell me what is involved in replacing the main shaft seal? I have quite a bit of oil accumulating on the undercarrage the tractor and some an oil ending up on the PTO. I also had a leaky valve cover which I resolved, but I believe there might be another leak given how much was under the mower. There is no oil puddling under on the pavement where the tractor is parked. Could this just have been from the valve cover? I have all the belts off right now and was taking a closer look at other leak possibilities. Removal of the PTO might be a little tricky as the bolt turns the motor, so I'm not sure what can be done to loosen it other than using an impact wrench. Does the motor need to be removed or any special tools required to replace this seal? I appreciate any assistance you can offer.

Answer
If the seal is leaking, then oil will pool up on the top of the pulley, then get slung everywhere
when started , so after it has been sitting a while reach up and feel in the top of the pulley
and if there is no oil, then the seal is probably fine.

   You can mimic the action of an impact wrench by just using a piece of wood rapping on the handle of your wrench, it will loosen it.