I got a Mamiya M645 a couple of weeks ago and thought I’d go look for a 80mm lens for it. Instead I found a Mamiya 645 super with 12 lenses, motor drive, a bunch of film backs, and a few other bits and pieces. All for a pretty decent price. One of the lenses (80mm f4 macro) has sticky shutters, and I’m wondering if they are hard to clean? Or expensive if I should have someone else do it?