Today, I opened the pill container and removed all the tiny screws I'd removed from the lenses with couplers, and sorted the shorter screws. First I did the f1.4, as one person said that it needed the short screws. I used the shortest two screws I had. Then I did the 24, 28 and 35 with no conflict between aperture ring and whatever lies beneath it. The 105 must need very short screws or likely 1.4mm washers. My shortest screws are too long. I can't find the post, but one person suggested a tiny square of double sided adhesive tape to hold the screw/screwdriver to get the screws started. My wife gave me a reel of 3/16" wide double sided tape she uses in scrapbooking and I did as the poster described, Brilliant solution, thank you very much! Now, can anyone suggest a source of 1.4mm washers?