Glad you figured oit out. Here are my thoughts on the cam...
The rangefinder coupling cam ( wedge-shaped) on Russian rangefinders is a very innovative and low cost approach to the finer engineering and machining skills of E. Leitz. Leitz uses a roller cam in the Leica. The roller gives smoother operation and a constant radius. Therefore it must be made very precisely. As a result the Leica needss only 2 rangefinder adjustment parameters, vertical and horizontal.
The Russian rangefinders have 3 parameters, vertical, horizontal-infinity and horizontal-near. The horizontal-near parameter is set by turning the wedge shaped cam. The cam has a variable radius, and this radius can be change by swiveling it on its base.
Some brave souls with steady hands use a pair of needle-nose pliers with rubber tips, or smooth (toothless) needle-nose pliers. Isaak Maizenberg recommends making a specialized but simple wrench to do the job.
I took a piece of photo-matte board and cut into a strip about 0.5 inches by 2 inches. I then drew the shape of the cam on one end and cut it out with a sharp Exacto knife. After doing this, check the fit on the cam.
If it fits, use this matte board wrench as a template and trace the outline on a piece of Lexan or Lucite about 3/32-1/8 inch thick. Cut the hole out. You now have a wrench.
Don’t make the wrench any wider than you need to accommodate the cut-out. If it is too-wide, it will not be able to move enough within the lens mount throat.
Focus the camera on a near object. Some people use 1 meter. I prefer to use a distance closer to what I ordinarily shoot at like 5 meters. Notre were the secondary image lies at this distance.
I am right-handed. To adjust the cam, remove the lens and hold the body in your left hand, upside-down. Use a fine tip permanent marker and put a reference mark on the top of the cam. This will allow you to see how much movement you are creating. Place the wrench over the cam and turn it, one way or another. Replace the lens and refocus. If the image moved farther apart, turn the cam the other way. Different positions have different radii, and so if you cannot get it to focus at one end of the cam, try the far end or the middle.
Sometimes the cam is loose or becomes loose during adjustments. In that case I use a dab of shellac on the pivot to tighten it up.
The usual progression to follow is as follows:
1. Set vertical image 2. Set near image 3. Set infinity image, 4. recheck near image, if it has to be moved again, follow-up by checking infinity image again, and so on.
Sometimes, no matter how hard you try, these Russian rangefinders will not agree between infinity and near focus. In that case, I opt to set the rangefinder for the best near focus and rely on depth of field for the infinity focus. This usually works well because infinity has lock.
-Paul