That very last screw you had so much trouble with is actually taken out through the focusing knob which has 2 hole in it once you take off the leatherete, remove a small center screw n the knob's plate.. unless the 2 holes line up through the knob.
No need to take the strap thing off only the outter ring nut so the side panel can come up over it.
Once the panel is lose, you'll have to sort of rotate it about a bit to clear the focusing knob n she is out. Now remove the lower panel held on by 2 screws near the bottom edge.
Once you get the outter panel off there is another shield to remove under these. The brass stand offs unscrew as well as the rest of the small screws near the bottom edge under the gooy foam seals. You also have to take off the bottom panel shield held on by 2 screws.
This tin sheild is very easily bent so take it easy getting it out. Carefully lift. The bottom one sort of lifts n then pulls off. All that gooy stuff has to be replaced.
Once inside you can watch the mechanisms n you should be able to figure out what is responsable for what as you cock it. The release is the criticle part I want you to look near the bottom right where it latches.
The repair manual makes it looks so scary, it actually not that bad once inside.. it'll all make sense once you see it.
How about e-mailing me?