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MTD
Gas Walk-Behind Mower

Model # 550 Official MTD lawn mower

Here are the diagrams and repair parts for Official MTD 550 lawn mower, as well as links to manuals and error code tables, if available.

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  • 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”.

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Model diagram and schematic

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Showing 10 of 65 parts  |
Craftsman Troybilt Lawn Mower 21-in Deck Mulching Blade (replaces 01002810, 742-0741a, 942-04276, 942-0741) 942-0741A
#24

Mower diagram

Craftsman troybilt lawn mower 21-in deck mulching blade (replaces 01002810, 742-0741a, 942-04276, 942-0741)

Part #942-0741A

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$27.71 | 
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Yard Machines Lawn Tractor Flange Nut (replaces 00012173, Wd-129-103) 712-04065
#43

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 | 
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Yard Machines Lawn Mower Handle Knob (replaces 01000382, 113589, 720-04072, 720-04125) 720-04072A
#9

Mower diagram

Yard machines lawn mower handle knob (replaces 01000382, 113589, 720-04072, 720-04125)

Part #720-04072A

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$9.33 | 
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Lawn & Garden Equipment Wing Nut 912-0397
#38

Mower diagram

Lawn & garden equipment wing nut

Part #912-0397

Replaced by #712-0397A

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Manufacturer substitution
This part replaces 912-0397. Substitute parts can look different from the original.
This item is not returnable
$5.22 | 
16% OFF Phone Price : $6.22
In Stock
Lawn & Garden Equipment Carriage Bolt (replaces 1186069, 583108, 706-101080, 706-10602-12, 791-182213) 710-0703
#12

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
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Lawn Mower Tie Cable 926-0240
#11

Mower diagram

Lawn mower tie cable

Part #926-0240

Replaced by #726-0178

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Manufacturer substitution
This part replaces 926-0240. Substitute parts can look different from the original.
This item is not returnable
$2.16
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Troybilt Lawn Mower Grass Bag (replaces 664-04027, 964-04007, 964-04011, 964-04034b, 964-04054, 964-04065, 964-04068, 964-04122) 964-04007A
#8

Mower diagram

Troybilt lawn mower grass bag (replaces 664-04027, 964-04007, 964-04011, 964-04034b, 964-04054, 964-04065, 964-04068, 964-04122)

Part #964-04007A

$143.25 | 
8% OFF Phone Price : $155.25
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Lawn Mower Screw 710-04531
#14

Mower diagram

Lawn mower screw

Part #710-04531

This item is not returnable
$7.77 | 
11% OFF Phone Price : $8.77
In Stock
Troybilt Lawn Mower Ground Drive Belt, 3/8 X 31-1/4-in 954-0637A
#51

Mower diagram

Troybilt lawn mower ground drive belt, 3/8 x 31-1/4-in

Part #954-0637A

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$17.69 | 
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Cable 746-04203
#50

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 | 
9% OFF Phone Price : $64.30
In Stock

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…

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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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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…

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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 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.…

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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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