Your clock has probably been running twenty-four hours a day for many years, and to some extent is worn. When worn severely, the holes in which the gears turn become enlarged. This allows a gear to lay down just a bit, and the teeth of one gear will no longer mesh properly with the next. There will be increased friction because of this and eventually the clock will stop. To repair worn holes correctly we use bushings.
Bushings are new holes put in place of the old worn holes.
First the original position of the hole is found. Then the hole is enlarged to accept a bushing, which is pressed in. When finished, the bushed hole is as good or better than new, and returns the gear to its original position. After all worn holes have been bushed, all pivots are inspected and repaired. If not refinished, a rough pivot can ruin even a new bushing in a few months time.