Hello all I have a John Deere 535e ztrak thats about 2 1/2 years old with 84 hours on the machine. I was cutting a few days ago when the all of the sudden the left side wheel started jerking a bit then lost almost all power. It had enough power to get it back to its parking space but now left side had no power. I believe it’s a hydrostatic transmission issue. Looks like there is no bolt to change trans fluid is this a closed system? I’m trying to trouble shoot why the left wheel lost power and if i need to buy and install a new left side trans?