Power Steering Issue
 

Hello, I recently purchased a 1968 Sport Satellite convertible with power steering. I noticed the power steering box was leaking and brought it to my trusted mechanic as I am not that mechanically inclined. I purchased a rebuilt power steering box from Buy Auto.com and my mechanic installed it. Unfortunately the steering was stiff and the steering wheel stays in what ever position you put it when turning and doesn't return to center on its own. The steering was fine before the replacement only the box was leaking. Thinking the rebuilt box was defective, I returned it and received another one and again had my mechanic install it. Same result, stiff steering with the wheel staying in what ever position you put it in not returning on it's own.

Any ideas besides finding a new mechanic? I open to that as well.

Thank you,