I bought a supposed Swedish military optical rangefinder made by NIFE, model 40 cm or A-40 It appears in good condition, images are crisp and the focus and range adjustment controls move and work, BUT, the small image which needs to align with the larger one is UPSIDE-DOWN. I do not know if I am simply doing something stupid, or if a reversing prism or mirror has fallen out of the optical path...I do not see how this could be and still have clear and approximately coincident images.... Allowing for the uncertainty of trying to line a right-side-up image with one upside-down, the actual ranges shown on the dial seem plausible. I'm looking for a little guidance as to what to look for, before I begin to take the thing apart Anyone know anything about these? Thanks!