Well, I think we might have a lead on your problem. The pins on my 180mm lens are 18mm long for the outside one, and 15mm long for the inside one. They are spring loaded however, and when I push them into the lens, they both stop at about 6mm. From your description of your lens, it sounds like the spring for those pins maybe be broken or not connected on your 180mm lens, and therefore not providing the right amount of pressure on the rangefinder mechanism. If your handy with tools, it looks like that cover comes off with just four screws.