The opening on the PTO side is under the 3 pt hitch top link mounting flange. You have to remove that to gian access. I didn't change the oil in the end. I bought the grass catcher used and figured that it would be a good idea to change the oil, but decided against it after removing the fill plug on the blower side, the oil was perfectly clean. Guess the unit saw light duty by the previous owner.
I'm all set up and ready for mowing as soon as the grass starts growing for real. Good to hear that you like your unit. I was a little uncertain whether it was a wise purchase. BTW, I saw someone's post, perhaps yours, about the castors on bar stock and made some out of wood. Makes a huge difference in the PITA factor when moving that thing around the garage.
Thanks for the reply.
S.