Steering problem

[snowman1Ohio]

I have a ventrac 4000 and when I am moving I can have the steering wheel straight not move it and the tractor will veer off to the right turn the wheel back tomthe left to straighten the tractor back out keep the steering wheel straight and it will veer off to the right again what might be my problem? Full of oil filters changed last year can't see anything broke.

 

[Dennis Mohn]

It has hydrostatic steering and may have a pressure differential to one side more than the other. Not unusual and the steering wheel may not always appear to be centered because of that.