21C, 21S, 25S,
30S & 38B Gasoline
Line Trimmers and
John Deere Horicon Works
LITHO IN U.S.A.
This manual is written for an experienced technician.
Essential tools required in performing certain service
work are identified in this manual and are
recommended for use.
Live with safety: Read the safety messages in the
introduction of this manual and the cautions
presented throughout the text of the manual.
N This is the safety-alert symbol. When you see
this symbol on the machine or in this manual,
be alert to the potential for personal injury.
Technical manuals are divided in two parts: repair
and diagnostics. Repair sections tell how to repair the
components. Diagnostic sections help you identify the
majority of routine failures quickly.
Information is organized in groups for the various
components requiring service instruction. At the
beginning of each group are summary listings of all
applicable essential tools, service equipment and
tools, other materials needed to do the job, service
parts kits, specifications, wear tolerances, and torque
Binders, binder labels, and tab sets can be ordered
by John Deere dealers direct from the John Deere
Distribution Service Center.
This manual is part of a total product support
TECHNICAL MANUALS—MACHINE SERVICE
COMPONENT MANUALS—COMPONENT SERVICE
Fundamentals of Service (FOS) Manuals cover basic
theory of operation, fundamentals of troubleshooting,
general maintenance, and basic type of failures and
their causes. FOS Manuals are for training new
personnel and for reference by experienced
Technical Manuals are concise guides for specific
machines. Technical manuals are on-the-job guides
containing only the vital information needed for
diagnosis, analysis, testing, and repair.
Component Technical Manuals are concise service
guides for specific components. Component technical
manuals are written as stand-alone manuals covering
multiple machine applications.