1957 Ford Y-block. With idle speed even slightly over specifications my power steering is giving no power. Drive belt OK, rebuilt control valve, no leaks, no noise. When I rise engine rpm slightly it´s beginning to help steering. Problem is worse with everything in normal working temperature.

The only part of the power steering I don´t know anything about is the pump. I bought it used when converting my car to power steering and it was said to be rebuilt but that could of course mean that just the seals have replaced. My question is:

Can the problem be the pump being worn internally so that it gives too low pressure at idle? Do they generally lose pressure with age and wear? Are there any rebuild kits to cure this or are the kits just for re-sealing? I think my pump is the Eton type with reservoir on top of pump but not sure.