72 K2500 Power Steering Problem

[54GMC150]

Greetings All,
I recently got my project truck running. Getting near to completion now. It has the original stock 800 Saginaw power steering box. When i started it Saturday(the first time in years since it ran), the steering wheel immediately and forcefully turned left fully. As yet,I’ve been unable to diagnose the problem. I removed the belt so I could test drive it and check various things and happily, everything is fine except for the stated problem. I am aware of the possibility of this happening with other types of power “assisted” steering like the system in a c3 corvette or ford type systems but this one has me stumped. Any ideas or insights would be very much appreciated. Thanks, Rick

[RustyPile]

Gummed up and stuck valves and other mechanisms in the gear box.. Might be able to free it up turning the steering wheel lock-to-lock with the front end jacked up and engine not running.. If you are familiar with the inner workings of the gear box, disassemble it, clean up everything, and put it back together with new seals..

[54GMC150]

Thanks Rusty I’ll try that.