Charles, I have a 70's vintage Zefal pump that also would not pump and needed a new cup seal. I looked up Zefal's web site and there was a place to ask a question. So I told them my problem and soon received an email that asked for a picture of the pump to identify it. I sent the picture, didn't hear anything for a week or two, asked again and he apologized and promptly sent me a new cup seal...no charge. The guy is in France and that's where he sent the part from!
pierre.yves.mercier@zefal.com Hope this will help you out.--Dave