Leitz was advised of slow shutter releases on Leica cameras in northern Norway during the winter of 1940/41. Leitz then replaced the pin bearings -- a simple hole in the crate with a simple pin going through it tos upport the shutter mechanism -- with a double ball-bearing race, thus founding the vaunted "IIIcK" camera. After the War, Leitz learned that only ONE side of the shutter needed to be made with ball bearings, and so Postwar IIIc's and all subsequent Leicas through the M6 had one pin-bearing shutter and one ball-bearing shutter. It is a LOT cheaper to use pin bearings than to use ball bearings! And bear in mind that Volkswagen developed a split Number 3 main at the same time to permit low-temperature operaton of its vehicles. VW scholars know that the #3 main is a rign bearing which is only installed when the crank is unscrewed. Well, VW STILL supplies a split #3 for air-cooled engines. I believe the 1600cc Zambonis use them.