MTD
Gas Walk-Behind Mower

Model #12A-979L401 MTD gas walk behind lawnmower

Here are the diagrams and repair parts for MTD 12A-979L401 gas walk behind lawnmower, as well as links to manuals and error code tables, if available.


There are a couple of ways to find the part or diagram you need:

  • Click a diagram to see the parts shown on that diagram.
  • In the search box below, enter all or part of the part number or the part’s name.

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

We encourage you to save the model to your profile, so it’s easy to access parts and manuals for your appliance whenever you log in.

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

Save to my profileOwner’s manual

Showing 10 of 192 parts

Lawn & Garden Equipment Bell Washer

#50

Handles e979 Diagram

Lawn & garden equipment bell washer

Part #736-0242
This item is not returnable
$3.05 | 
20% OFF MSRP:$3.80

In Stock

Lawn Tractor Screw

#1

Transaxle assembly Diagram

Lawn tractor screw

Part #710-0134
This item is not returnable
$2.80 | 
28% OFF MSRP:$3.90

In Stock

Lawn Mower Hex Screw, 1/4-15 x 1-in

#43

Transaxle assembly Diagram

Lawn mower hex screw, 1/4-15 x 1-in

Part #710-1241
This item is not returnable
$4.27 | 
16% OFF MSRP:$5.10

In Stock

Lawn & Garden Equipment Hex Screw

#17

Transaxle assembly Diagram

Lawn & garden equipment hex screw

Part #710-0896
This item is not returnable
$2.83 | 
12% OFF MSRP:$3.20

In Stock

Lawn & Garden Equipment Flat Washer

#6

Transaxle assembly Diagram

Lawn & garden equipment flat washer

Part #736-0204
This item is not returnable
$2.91 | 
9% OFF MSRP:$3.20

In Stock

Lawn & Garden Equipment Hex Cap Screw

#16

Transaxle assembly Diagram

Lawn & garden equipment hex cap screw

Part #710-0751
This item is not returnable
$2.71 | 
13% OFF MSRP:$3.10

In Stock

Lawn & Garden Equipment Flat Washer

#4

Transmission Diagram

Lawn & garden equipment flat washer

Part #736-3084
This item is not returnable
$3.68 | 
6% OFF MSRP:$3.90

In Stock

Lawn & Garden Equipment Bolt

#1

Handles 959/979 Diagram

Lawn & garden equipment bolt

Part #710-1174
This item is not returnable
$4.86 | 
13% OFF MSRP:$5.60

In Stock

Lawn & Garden Equipment Machine Screw

#8

Handles 959/979 Diagram

Lawn & garden equipment machine screw

Part #710-0605
This item is not returnable
$2.84 | 
14% OFF MSRP:$3.30

In Stock

Lawn Tractor Screw

#21

Transmission Diagram

Lawn tractor screw

Part #710-0642
This item is not returnable
$2.89 | 
10% OFF MSRP:$3.20

In Stock

Symptoms for gas walk-behind mowers

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

Main causes: drive control cable failure, worn or broken drive belt, bad transmission, broken drive wheel
Main causes: uneven wheel height settings, damaged wheel, dull or damaged cutting blade
Main causes: dirty carburetor, bad spark plug, clogged air filter, engine choke problems, clogged gas cap vent
Main causes: damaged cutting blade, loose cutting blade, damaged flywheel key, engine needs tune up
Main causes: engine needs tune up, dirty or clogged carburetor, damaged flywheel key
Main causes: stale gas, engine needs tune up, bad spark plug, dead battery, bad recoil starter, faulty safety switch, bad ignition coil

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.

How to replace a lawn mower flywheel key on an OHV engine

The flywheel key couples the flywheel to the engine crankshaft. Replace the flywheel key if it's broken.

Repair difficulty
Time required
 60 minutes or less
April 1, 2013
By Lyle Weischwill
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.

Repair difficulty
Time required
 15 minutes or less
April 1, 2013
By Lyle Weischwill
How to replace a lawn mower safety switch

The safety switch stops the engine when you release the lever on the handle. This repair guide explains how to replace it if it's not working correctly.

Repair difficulty
Time required
 30 minutes or less

Articles and videos common to all walk-behind mowers

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

October 1, 2019

Types of walk-behind mower blades video

By Sears PartsDirect staff

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