Why not try Back Flushing the nozzle first,take the pipe off the nozzle hold it on the jet where it squirts out if you have enough tube,then operate the pump,or take the pipe off fill a washing up bottle with water push it on the jet and squeeze,ten mins and nothing lost,while your there leave the pipe off, point it to the ground and pump the water out,you may have a bit of muck in the pipe that keeps pushing up and blocks the jet.don't dismantle if you can try other things first
Rich
March 2010