fraley
Beware of Claws
Thanks to the Zorki 4 pop-the-top drawing at http://rick_oleson.tripod.com/index-58.html I popped the top on my Zorki 4. I wanted to get at the debris on the viewfinder/rangefinder glass. I feel like I cheated the gods, as I got it apart & cleaned, AND back together again with no extra pieces left over 
One thing I didn't catch onto at first - the film advancement knob comes off by turning it in the opposite direction of regular film advancement, once you've loosened the set screw. I did try pulling it off but that didnt' work so I did another search on "Zorki repair" and found a reference here http://cameras.alfredklomp.com/zorkis/repair/ to rotating the knob against the direction of the arrow. The only other sticky part was that my smallest screwdriver was a wee bit snug for the set screw on the synch ring, but it came loose eventually.
There's a metal L-shaped piece holding the rear viewfinder/rangefinder glass in place. Two screws on the bottom of it come out, lift it up, and you can get at the diopter glass and inner viewfinder glass. The other rangefinder glass connected to the cam arm is easy to access.
I did this on a camera that I was willing to live with the consequences if I broke anything, always a good idea for me before I dive in... but it turned out okay. I'd recommend giving it a try on a spare Zorki if you have one.
One thing I didn't catch onto at first - the film advancement knob comes off by turning it in the opposite direction of regular film advancement, once you've loosened the set screw. I did try pulling it off but that didnt' work so I did another search on "Zorki repair" and found a reference here http://cameras.alfredklomp.com/zorkis/repair/ to rotating the knob against the direction of the arrow. The only other sticky part was that my smallest screwdriver was a wee bit snug for the set screw on the synch ring, but it came loose eventually.There's a metal L-shaped piece holding the rear viewfinder/rangefinder glass in place. Two screws on the bottom of it come out, lift it up, and you can get at the diopter glass and inner viewfinder glass. The other rangefinder glass connected to the cam arm is easy to access.
I did this on a camera that I was willing to live with the consequences if I broke anything, always a good idea for me before I dive in... but it turned out okay. I'd recommend giving it a try on a spare Zorki if you have one.