Altman's angle stop valves

[bobbobwhite]

http://www.altmansproducts.com/

I have Altman's high end, Ottley collection angle stop valves in my remodelled bath in both shower and sink. They are so hard to open and close! My wife chose round knobs and I can't open and close them with wet hands. I have to dry my hands to use them and it is still a chore. Very stiff and not at all like Moen, etc. I can't change them out as they were chosen by a "designer" my wife hired.

Is there a way to loosen the friction of these angle stops, or will I have to replace the knobs with expensive levers to solve?

Thanks.