I just finished adding saginaw steering to my '73 fj40, 350 sbc. The front end is on jackstands, and when I fired it up for the first time,the belts squeaked for a second then it sounded ok.Then the steering started turning on its own to the left and locked up. I turned it off, it released the pressure and loosend up. Started it back up and did the same thing. Pump is new, hoses are new, box is junkyard '68 Impala. Bad box? ???