[Lynn Eades]

With two bits of flat steel clamped across the two lugs with two pair of vice grips, rotate the steel/ vice grips in an anti clockwise direction, as you look down on the cap if you haven't damaged the housing, it should unscrew. Go to a brake shop for a better quality cap (alloy type) Put some plastic film over the hole to keep the dirt out and take your cap as a sample.