You can take a clean, soft tissue with a bit of water on it. (Do NOT use alcohol because the 45 degree transparent mirror will lose its ability to reflect.) With a Q-Tip you can gently clean all of the VF and mirror, because those items develop a coating from years of being exposed to the air (like the inner elements of a lens which, likewise, can develop that coating).
Please excuse me eliot, but I did not read your original post with sufficient care: you indicate that the horizontal data is correct but that the vertical is not. My answer, in the paragraphs below, pertains to horizontal alignment, not vertical. As for vertical, there should be another screw (or two) that tilts the actual mirror near the front center of the top where the image comes into the camera a second time. To explain, the viewfinder takes in the image, but also, the same image (from a very slightly different angle) also comes into the rangefinder from another window near the front-center of the camera. The mirror near that second window is what I am talking about, here. THAT mirror needs to be tilted VERY slightly either up or down and there has to be a screw (or two) that do this. I cannot remember just where that adjustment is on this particular camera, but if you gently try to tilt that mirror while looking through the viewfinder, you will see the image tilt either up or down. Naturally, you want the vertical to also be in alignment.
Now, for horizontal adjustments:
You must first find out whether the camera's apparent focus (what the RF says is in focus) is what is REALLY in focus (what the film plane indicates). If it is, no adjustment need be made. If there is a discrepancy, you must do this:
Photograph a 45 degree object (the back of an LP album is great, as is a picket fence, or some other object that has detail throughout. The purpose is to focus at the dead center and, after processing, to see what is ACTUALLY in focus (according to the negative's image at the film plane). Now you know whether the REAL focus is before, or behind, the RF focus, and by how much.
Then place the camera back on the tripod (make certain to place that tripod exactly where it was) and re-focus back at the dead center. NOW, THIS TIME, you know that that center is NOT REALLY in focus (even though the RF says that it is), but, luckily, you know what REALLY is in focus. With the RF focus set at dead center of the object, adjust that screw so that the focus merge in the RF happens not at the center (as falsely indicated by the RF), but now at the location that the film plane has indicated after processing the negative. Then you will have corrected your RF so that it matches the 'film plane reality'.
You must always remember that what changes that RF indication is a pin on the lens that is mechanically governed solely by how far that lens is from the film plane. That distance, and ONLY that distance, is what determines (real, not apparent) focus in your camera. What the RF merely indicates is in focus is but an indicator, and is not necessarily perfectly matched to the REAL focus, proven by the film plane's imprinting of the image.
May I now try to fight my way out of the few flakes of snow that have fallen in Philadelphia? - David Lyga
