Thanks guys!
I wipe my camera clean after each use too, but yesterday when I was using it to photograph some maple leaves, I think dirt or maybe sap may have gotten under that shutter when I was using it on the ground.
Anyway---
Here's what I wound up doing:
I took the shutter off.
But first I noted the position of the slot of each screw so I could re-assemble it just like it was prior to taking apart.
Next I noted how many turns it took to get each one of the screws off the camera.
In my case, the tension screw was 3 full turns and the holding screw was 4 full turns.
Then,
I put _one_ drop of "Murphy's Oil soap" (mild vegetable based soap) in a 1/4 cup of warm water and swished it around until it was thoroughly mixed.
Then I dipped a cotton bud in the mixture and gently wiped the surfaces. No gunk came off, but even better the nice finish on the wood didn't come off either!
After re-asembly the shutter does work better,
but I think the real issue is that some of the gloss finish has worn off the shutter just below the screws and is what is causing the small amount of drag that I still have. It's not too bad, and still very usable, but it's not like it was when it was new.
I'm going to contact Zero Image and see if they will send me a replacement shutter.
Thanks again for the tips!
Becky