When replacing gears and installing a new mesh/belt, make sure the following:
1. Gears are installed on the shaft in such a way that the grooves on adjacent gears shifted in different directions. This is achieved by turning the gears of one or the other side when installing on the shaft. Bushings are installed between the gears.
2. The groove on the first gear from the pulley must be shifted to the left, the groove of the second gears - to the right and so on (top view, arrows show directions displacement):