Mercury Rotor Assy - 13524B5. Keep your Mercury engine firing on all cylinders with the Mercury Rotor Assembly (Part #13524B5). This genuine OEM ignition rotor is built to exact Mercury specifications for consistent spark distribution, optimal engine timing, and long-lasting performance in marine environments. Whether you're performing scheduled maintenance or troubleshooting ignition issues, this rotor assembly delivers dependable function you can trust.. Key Features. OEM Quality - Designed by