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MTD
Gas Walk-Behind Mower

Model # 12A-446B729 Official MTD lawn mower

Here are the diagrams and repair parts for Official MTD 12A-446B729 lawn mower, as well as links to manuals and error code tables, if available.

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Owner’s manual

Model diagram and schematic

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ALL PARTS
Showing 10 of 72 parts  |
Blade-21" Mu 742-0741
#24

Lawn 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 | 
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Knob 720-04072
#9

Lawn 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.
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$9.33 | 
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Wheel Asm-8 634-0190
#32

Lawn mower diagram

Wheel asm-8

Part #634-0190

Replaced by #634-0190A

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Manufacturer substitution
This part replaces 634-0190. Substitute parts can look different from the original.
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Yard Machines Lawn Mower Wheel 734-1987
#17

Lawn mower diagram

Yard machines lawn mower wheel

Part #734-1987

$26.80 | 
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Wing Nut 712-0397
#38

Lawn mower diagram

Wing nut

Part #712-0397

Replaced by #712-0397A

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Manufacturer substitution
This part replaces 712-0397. Substitute parts can look different from the original.
This item is not returnable
$5.22 | 
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Cable Tie 726-0240
#11

Lawn mower diagram

Cable tie

Part #726-0240

Replaced by #726-0178

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Manufacturer substitution
This part replaces 726-0240. Substitute parts can look different from the original.
This item is not returnable
$2.16
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Lawn Mower Screw 710-04531
#60

Lawn mower diagram

Lawn mower screw

Part #710-04531

This item is not returnable
$7.77 | 
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Cable 746-04203
#50

Lawn mower diagram

Cable

Part #746-04203

Replaced by #946-04203

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Manufacturer substitution
This part replaces 746-04203. Substitute parts can look different from the original.
$58.30 | 
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V-belt 754-04101
#51

Lawn mower diagram

V-belt

Part #754-04101

Replaced by #954-0637A

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Manufacturer substitution
This part replaces 754-04101. Substitute parts can look different from the original.
This item is not returnable

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$17.69 | 
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Bail 747-1161A
#1

Lawn mower diagram

Bail

Part #747-1161A

Replaced by #747-1161A-0637

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Manufacturer substitution
This part replaces 747-1161A. Substitute parts can look different from the original.
This item is not returnable
$20.10 | 
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Symptoms for gas walk-behind mowers

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

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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…

Read more

Why does my lawn mower cut unevenly?

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

Read more

Why does my lawn mower run rough?

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

Read more

Why won't my lawn mower move?

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

Read more

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 stall?

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

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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 rebuild a lawn mower carburetor

How to rebuild a lawn mower carburetor

The carburetor mixes air with fuel to drive the piston. Rebuild the carburetor if it's clogged or leaks.…

Read more
Repair difficulty
Time required
 60 minutes or less
How to replace a lawn mower recoil starter on an OHV engine

How to replace a lawn mower recoil starter on an OHV engine

Replace the recoil starter if it doesn't move when you pull the starter rope.…

Read more
Repair difficulty
Time required
 15 minutes or less
How to replace a lawn mower wheel

How to replace a lawn mower wheel

Learn how replace a damaged wheel on a walk-behind lawn mower—it's a quick, easy fix.…

Read more
Repair difficulty
Time required
 15 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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How to enjoy all the online benefits we offer on our Sears PartsDirect website

How to enjoy all the online benefits we offer on our Sears PartsDirect website

Learn about all the convenient features on our Sears PartsDirect website that make your parts purchases easier.…

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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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Types of walk-behind mower blades video

Types of walk-behind mower blades video

Learn about the different kinds of mower blades and how to maintain them.…

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