To see the videos referenced in the post, visit the ClockSavant Instagram page. I recently serviced this beautiful 1945 Universal Geneve (UN) reference 22278 calibre 281 vintage chronograph for a ClockSavant customer. While I am very passionate about vintage chronographs from this renaissance period, their mechanisms have frequently received significant abuse from wear and past failed servicing and need a good deal of attention. The "programming" of the chronograph, which is done through “eccentrics" or “eccentric screws” are often fouled due to past improper adjustment, wear, and replacement parts incompatibility. Correcting all of this requires a high pain threshold and a great deal of experience and understanding of the interrelationships and dynamics of the movement. Relative to parts interoperability, as one example, I show two minute jumpers having drastically different characteristics yet both can be interpreted as "correct" based on published materials for this particular calibre. This is one of the finest chronograph movements made during this era but it lacks eccentric screw adjustability for depth of reset hammer penetration into the cam hearts of the seconds and minute chronograph wheels. In some cases you must fabricate a replacement screw for the flyback lever to assure proper reset, cut to the precise size required within fractions of a millimeter, to assure the flyback hammer penetrates the cam hearts perfectly. In the pictures, I show a slow motion video from the back of the movement during the final stages of servicing. While you can't see it fully, the watch is operating correctly but is not meeting my standards-- too much shake on the minute wheel. Next I show a video after all optimization is completed across the movement, demonstrating precise and crisp reset. After servicing, this watch is now running superbly once again and its chronograph can be used reliably to time important events.
