When you are in sand, it gets into the clutch bell and gets between the clutch shoes and the bell causing the clutch to slip. The consequence is a worn out clutch and enough heat generated and passed through the pinion to melt the spur gear. Your plastic pinion and clutch bell holder is probably ruined and the bearings too.

The solution is a covered clutch that will not allow sand to get to the shoes. That is one of the reasons the turtle clutch system is so popular.

Dennis