Thanks for the responses...Jim: yes it does happen with any subject, and no, I can't post samples--I'm just not there with gear and knowledge. However, I did cruise David Odess's FAQ site www.david-odess.com/faq.hml , and I see reference to changing the nylon stop along with light seals in backs. Some of what Mr. Odess describes seems to apply to stops. I just finished a roll of color film (in Maine USA, that's easy to do), and I should have it back from the lab on Tuesday. At that point, if the problem persists I will send both of the backs, the body, and the film to Hasselblad Service in New Jersey (it means giving up a few meals again, but what's more important eating or photography?). David Odess, in case any USA HUG'ers aren't aware, is purported to be a premier repair man, but he doesn't do focal plane cameras (hence Hasselblad service in NJ).