Ransomes TwinTrak xt2030 - steering issue

I bought this unit knowing it had a blown onan engine - just got it rebuilt and it runs great but when I engage the drive and pull back on the right steering lever it goes forward and backward when I move it forward, and the left lever does the opposite?? According to the parts manual, I don't have a user manual, it appears the drive belt layout is correct and don't think it is possible to change rotation of the pumps via the belt ... any ideas what could cause this? I have two other Ransomes but not zero turn units and they are great ... would like to get this one working for use at the cabin.
Thanks a Bunch!