The sideshake is the level of the play in a jewel-hole pivot. A sideshake can be beneficial to the gear as long as it is minimal. It is what caused the gear to turn. On the other hand, excessive sideshake can lead the gear teeth to clash which can stop the watch. A watch normally causes minimal sideshake. If the sideshake is too much, it means that the pivots are worn due to usage or due to poor lubricated jewels.