If you follow the sticky "HOW TO - Zorki 4K CLA" it'll get you pretty close to being able to get at the shutter curtains - you just need to remove the RF to get at one of the top plate screws. After that, ZorkiKat's site will show you the rest. Underneath the additional complexity the shutter is pretty much the same on later FEDs and Zorkis as the early ones. It's tedious and fiddly but not difficult. The bit that'll try your patience is reassembling the parts into the crate whilst keeping the curtains, laths etc all in the right relative positions!
Zorki: 1e (x2), 2C, 3M, 4, 4K, 5, 6
FED: NKVD, 1g, 2e, 3a, 3b, 4L (x2), 5B, 5C
Kiev 4, 4A
Yashica Minister III
Zenith C, Zenit C, Zenit E
Minolta XG M, Z1
"The way to see by faith is to shut the eye of reason."- Benjamin Franklin