zero turn

I have a Toro MyRide 54 zero turm mower and the left transmission gets noisy and weak after mowing for 30 minutes or so. I can't find a dipstick, fill plug, or filter on this model. Does anyone know how to check the fluid or have had a similar issue?

Hi, I'm from SC so never mowed anything that wasn't flat. Have a good sized yard around the house that sits on a hill. Guessing around half an acre or so. What's the consensus? I have a zero turn SCAG that has the perpetually leaking B&S 25hp commercial; great mower otherwise. Suggestion box is...