Repairs Right wheel goes in forward and reverse, left wheel nothing

I have an Exmark Quest that's about 10 years old, 4500 series. Everything worked good last year. Went to mow this year and the right side wheel operates fine in forward and reverse. Left wheel doesn't respond at all. Also noticed an oil leak from the reservoir area. Wondering if a leak would case it to stop working entirely. And my bypass levers are both in the correct position. And yes, the parking brake is released. First thing that I checked. And I can manually move the left tire both in both forward and reverse. Any help would be greatly appreciated.

Repairs Right wheel goes in forward and reverse, left wheel nothing