Another frequent problem happens with Jaw Crusher is the mobile jaw plate jumps while it is crushing.
It is mainly because the mobile jaw plate is not fastened to the moving jaw. You would better stop the machine, and fasten the moible jaw plate to the moving jaw. This will do.
The fixed jaw plate sometimes jumps too. The reason of this phenominon is simillar to the mobile jaw plate. We need to the fasten the bolts on the fixed jaw plate.