I was taking the backing plate off my 6 inch Griot in preparation for putting a 2 7/8 backing plate on that I had just ordered. I could find no where to put a wrench which I thought was very odd. I noticed four small screws in the backing plate and decided that these had to come out. Three came out with some force and the fourth one stripped. The metal on these screws was very low strength. I decided to drill it out and to make a long story short damaged the backing pad. I thought no big deal I will just buy a new backing plate. It was then that I realized that a new plate will not fit. This was not meant to come off. Apparently I have a old model that does not have a replaceable backing plate. The screw holes are undamaged but there is no way to buy the actual backing disc that has four mounting screws. Bad day in Utah!:wall