Dishwasher spray arms not spining

I have a GE dishwasher/ top and middle arms don't rotate/what is the 3/16 hole at the point of connection of the vertical pipe and the horizontal pipe that goes to the middle sprayer. The hole continues thru the back wall ofthe washer.Is this for a screw to hold the pipe(conduit) to the back wall or for some other reason having to do with the non rotating sprayers