Mercury Manual-Service - 90-896579TK1. The Mercury Manual-Service - 90-896579TK1 is the official service guide designed for technicians and DIY boaters who maintain and repair Mercury marine engines. This detailed manual provides comprehensive, model-specific procedures straight from the manufacturer, helping you diagnose issues accurately and perform repairs with confidence.. Key Features. OEM Service Manual - Authored by Mercury Marine for precision and reliability. In-Depth Repair Instruction