Ultimate's bike stand biz was acquired by Feedback Sports about 7 years ago. Looking at
their website it seems most if not all of the older Ultimate designs have been replaced. It's not at all clear on their website what, if anything, might be interchangeable between the new Feedback and older Ultimate stands. You might try contacting Feedback directly with your stand info, and see if they can be of any help.
Another option for the clamp - if you go into about any long-standing LBS with a busy repair dep't, take note of the clamps on the stands. Many of those I've seen have been re-padded with foam that is then wrapped heavily with either vinyl electrical tape or tan/brown plastic packing tape.