This document contains sections and groups related to service information for John Deere 21-inch rear discharge walk-behind rotary mowers. It includes specifications for various mower models, repair specifications for engines and components, information on fuels and lubricants, and locations for identifying serial numbers. The document outlines sections for engine repair, fuel/air systems, electrical systems, power trains, tests and adjustments, and miscellaneous repairs. It provides technicians with information needed for diagnosis, repair, and maintenance of the mowers.