Sounds great - by the way, I just searched APUG with "mamiya 180mm stuck shutter" and did find a post from you (but it was an 'email me"). Mamiya RB stuck shutter did come up with a rough-ish rundown - if there's a decent post here that will save you some time, feel free to point me.

I wouldn't be surprised if I'm fine getting the shutter exposed and then will need to take some pics to suss out what's wrong. I do have a nice macro lens for my DSLR though...