hi i wanted to get all the swirl marks out of my a3 using meguiars scratch-x. i descided to get used to it first before i attept the car so i did the van with t-cut first, well i only managed to do the bonnet and my grinder was burning out, i was using a medium sponge (blue). i thought my grinder was to small but, ive had a look on ebay and they sell the 5' grinders in a kit for detailing. my grinder is a performance power (B&Q) 860w. what am i doing wrong or what sort of wattage grinder do i need?