When we restore a clock movement, it is completely dissasembled and ultrasonically cleaned. Pivots (gear shaft ends) are polished and bushings are installed where needed. If the movement is powered by springs, they are cleaned, inspected and replaced if needed. It is then test run and regulated.
Many clocks over 50 years old have had some sort of work done at some point in their life. Some early repair procedures were carried out in the simplest and most cost-effective way, not giving much thought to the future value of the clock. In the interest of just getting the job done, some "repair" shops still use these procedures.
One of the most common types of wear is when the gear shaft end (called the pivot) grinds the normally round hole into an oblong shape. This causes the gears attached to the shafts to mesh differently, robbing power which is needed to run the clock. The photos above show the most common "repair" - pushing the pivot back into place by using a punch. This type of work not only scars the mechanism but doesn't last as long as installing a bushing (more on bushings later). Punching the brass back into place is no longer an accepted repair technique.
Another patch job to get the clock going is the use of some sort of "band-aid". This is used to move the pivot back into place by attaching a piece of metal adjacent to the pivot hole. Usually a flat piece of brass or sometimes even a paper clip was used. The resulting repair is not only ugly, but also can wear the pivot as shown in the photo above. Even after a proper repair, there are usually scars.