Brake fluid on a rag... Then sand till you have uniform scratch marks, at like 1200. Then use a wool buffing pad at 1500 rpms w/ 3m buffing compound on a rotary buffer, then go to lighter pads, until you get to final polishing stages.... It's an ass ton of work, like said previously just get the paint off and sand and clear.... or get new plastics. Too many cheap sets of plastic out there...