hey mule, that is not the nut you want..the one you want takes a 10 mm wrench and it is the actual adjuster nut on the cable that locks the cable to the bracket...(there are two nuts-one on each side of the bracket)just loosen the nut closest to the pump arm...once it is unthreaded you can pull the cable out of the bracket and then use the extra cable slop to turn the end in the pump arm until it pops out of the arm..then reverse the install....when all done the marks on the arm and pump should be lined up ...