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Troybilt
Gas Walk-Behind Mower

Model # 420 Official Troybilt lawn mower

Here are the diagrams and repair parts for Official Troybilt 420 lawn mower, as well as links to manuals and error code tables, if available.

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Not all parts are shown on the diagrams—those parts are labeled NI, for “not illustrated”.

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For DIY troubleshooting advice and repair guides, visit our repair help section.

Owner’s manual

Model diagram and schematic

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ALL PARTS
Showing 10 of 48 parts  |
Blade-21" Mu 742-0741
#23

Rotary mower diagram

Blade-21" mu

Part #742-0741

Replaced by #942-0741A

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Manufacturer substitution
This part replaces 742-0741. Substitute parts can look different from the original.
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$29.10 | 
17% OFF Phone Price : $35.10
In Stock
Lawn Mower Blade Support (replaces 936-0524a) 736-0524B
#26

Rotary mower diagram

Lawn mower blade support (replaces 936-0524a)

Part #736-0524B

Replaced by #736-0524B-1

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Manufacturer substitution
This part replaces 736-0524B. Substitute parts can look different from the original.
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$6.58 | 
13% OFF Phone Price : $7.58
In Stock
Yard Machines Lawn Tractor Flange Nut (replaces 00012173, Wd-129-103) 712-04065
#42

Rotary mower diagram

Yard machines lawn tractor flange nut (replaces 00012173, wd-129-103)

Part #712-04065

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This item is not returnable
$5.27 | 
16% OFF Phone Price : $6.27
In Stock
Knob 720-04072
#9

Rotary mower diagram

Knob

Part #720-04072

Replaced by #720-04072A

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Manufacturer substitution
This part replaces 720-04072. Substitute parts can look different from the original.
BEST SELLER
$9.33 | 
10% OFF Phone Price : $10.33
In Stock
Lawn Mower Control Cable 746-1130
#33

Rotary mower diagram

Lawn mower control cable

Part #746-1130

Replaced by #946-1130

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Manufacturer substitution
This part replaces 746-1130. Substitute parts can look different from the original.
This item is not returnable
$14.49 | 
12% OFF Phone Price : $16.49
In Stock
Lawn & Garden Equipment Carriage Bolt (replaces 1186069, 583108, 706-101080, 706-10602-12, 791-182213) 710-0703
#12

Rotary mower diagram

Lawn & garden equipment carriage bolt (replaces 1186069, 583108, 706-101080, 706-10602-12, 791-182213)

Part #710-0703

This item is not returnable
$6.46 | 
13% OFF Phone Price : $7.46
In Stock
Yard Machines Lawn & Garden Equipment Wing Nut (replaces 01002925, 920-0279) 720-0279
#5

Rotary mower diagram

Yard machines lawn & garden equipment wing nut (replaces 01002925, 920-0279)

Part #720-0279

This item is not returnable
$6.87 | 
13% OFF Phone Price : $7.87
In Stock
Yard Machines Lawn & Garden Equipment Guide Bolt 710-1205
#6

Rotary mower diagram

Yard machines lawn & garden equipment guide bolt

Part #710-1205

This item is not returnable
$5.01 | 
17% OFF Phone Price : $6.01
In Stock
Blade Adapter 748-0377C
#22

Rotary mower diagram

Blade adapter

Part #748-0377C

Replaced by #748-0377E

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Manufacturer substitution
This part replaces 748-0377C. Substitute parts can look different from the original.
This item is not returnable
$26.00 | 
19% OFF Phone Price : $32.00
In Stock
Lawn Mower Lower Handle (replaces 749-0928a-0637) 749-0928A
#4

Rotary mower diagram

Lawn mower lower handle (replaces 749-0928a-0637)

Part #749-0928A

Replaced by #749-0928A-0637

?
Manufacturer substitution
This part replaces 749-0928A. Substitute parts can look different from the original.
$45.60
In Stock

Symptoms for gas walk-behind mowers

Choose a symptom to see related walk-behind mower repairs.

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Why won't my lawn mower move?

Main causes: drive control cable failure, worn or broken drive belt, bad transmission, broken drive wheel…

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Why does my lawn mower run rough?

Main causes: engine needs tune up, dirty or clogged carburetor, damaged flywheel key…

Read more

Why does my lawn mower stall?

Main causes: dirty carburetor, bad spark plug, clogged air filter, engine choke problems, clogged gas cap vent…

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Why does my lawn mower vibrate a lot?

Main causes: damaged cutting blade, loose cutting blade, damaged flywheel key, engine needs tune up…

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Why won't my lawn mower start?

Main causes: stale gas, engine needs tune up, bad spark plug, dead battery, bad recoil starter, faulty safety switch, ba…

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Why does my lawn mower cut unevenly?

Main causes: uneven wheel height settings, damaged wheel, dull or damaged cutting blade…

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Repair guides for gas walk-behind mowers

These step-by-step repair guides will help you safely fix what’s broken on your walk-behind lawn mower.

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How to replace a lawn mower spark plug

How to replace a lawn mower spark plug

Take a few minutes to replace the spark plug during your lawn mower's annual tune-up or if the spark plug is burnt or cr…

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Repair difficulty
Time required
 15 minutes or less
How to replace a lawn mower drive cable

How to replace a lawn mower drive cable

The drive cable engages the transmission to spin the drive wheels and move the mower across the grass. Replace the drive…

Read more
Repair difficulty
Time required
 60 minutes or less
How to replace a lawn mower starter rope

How to replace a lawn mower starter rope

These step-by-step instructions show how to replace a broken starter pull rope on a walk-behind lawn mower.…

Read more
Repair difficulty
Time required
 30 minutes or less

Effective articles & videos to help repair your walk-behind mowers

Use the advice and tips in these articles and videos to get the most out of your walk-behind lawn mower.

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Tapping into a new feature in the Search Bar on Sears PartsDirect

Tapping into a new feature in the Search Bar on Sears PartsDirect

Learn about a new feature added to the Search Bar on Sears PartsDirect…

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Introducing new technical repair content that we’re developing for the Sears Technical Institute

Introducing new technical repair content that we’re developing for the Sears Technical Institute

Learn about Sears Technical Institute and the advanced technical content being developed for aspiring appliance techs.…

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Top questions about Sears and Sears PartsDirect

Top questions about Sears and Sears PartsDirect

Get answers to frequently asked questions about Sears and Sears PartsDirect.…

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