Dixie hydro problem?

I have a 1989 xw2000 60 inch dixie. I was mowing when I lost steering in the left side. I assume it is the hydro pump as opposed to the wheel motor. I made that assumption due to the fact that when I move the left handle forward or reverse, nothing happens, not even the the grinding sound from the hydro. However the right side works perfectly along with making the normal grinding sound. If anyone has any idea whats happening with my dixie I would sure appreciate your input.

Simple things first, check the bypass valve and then check that the pulley is turning the pump