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Troybilt
Rear-Tine Tiller

Model # 21A-644H766 Official Troybilt tiller

Here are the diagrams and repair parts for Official Troybilt 21A-644H766 tiller, 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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Showing 10 of 127 parts  |
Lawn Tractor Screw (replaces 01000628, 01000865, 1186307, 1186308, 791-180288, 791-683298, 910-0599) 710-0599
Lawn tractor screw (replaces 01000628, 01000865, 1186307, 1186308, 791-180288, 791-683298, 910-0599)

Part #710-0599

BEST SELLER
This item is not returnable
$4.91 | 
17% OFF Phone Price : $5.91
In Stock
Lock Washer 736-0119
Lock washer

Part #736-0119

Replaced by #936-0119

?
Manufacturer substitution
This part replaces 736-0119. Substitute parts can look different from the original.
This item is not returnable
$6.05 | 
14% OFF Phone Price : $7.05
In Stock
Lawn Tractor Hex Bolt 710-3008
Lawn tractor hex bolt

Part #710-3008

This item is not returnable
$4.62 | 
18% OFF Phone Price : $5.62
In Stock
Lawn & Garden Equipment Cable Tie 725-0157
#13

Handlebar/cable diagram

Lawn & garden equipment cable tie

Part #725-0157

Replaced by #726-0178

?
Manufacturer substitution
This part replaces 725-0157. Substitute parts can look different from the original.
This item is not returnable
$2.16
In Stock
Ace Lawn & Garden Equipment Flange Lock Nut 712-3004A
#7

Tine hood/transmission diagram

Ace lawn & garden equipment flange lock nut

Part #712-3004A

This item is not returnable
$4.92 | 
17% OFF Phone Price : $5.92
In Stock
Ace Lawn & Garden Equipment Flat Washer 736-3078
#38

Engine bracket/belt/cover diagram

Ace lawn & garden equipment flat washer

Part #736-3078

This item is not returnable
$6.26
In Stock
Oil Seal 721-04030
#7

Transmission housing assembly diagram

Oil seal

Part #721-04030

Replaced by #921-04030

?
Manufacturer substitution
This part replaces 721-04030. Substitute parts can look different from the original.
This item is not returnable
$15.89 | 
11% OFF Phone Price : $17.89
In Stock
Sears Snowblower Flat Washer (replaces 936-0159) 736-0159
#1

Engine bracket/belt/cover diagram

Sears snowblower flat washer (replaces 936-0159)

Part #736-0159

This item is not returnable
$5.73 | 
15% OFF Phone Price : $6.73
In Stock
Screw 710-0106
#17

Handlebar/cable diagram

Screw

Part #710-0106

This item is not returnable
$5.80
In Stock
Lawn & Garden Equipment Hex Bolt 710-0597
#2

Tine hood/transmission diagram

Lawn & garden equipment hex bolt

Part #710-0597

This item is not returnable
$5.80
In Stock

Most common symptoms to help you fix your tillers

Choose a symptom to see related tiller repairs.

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Why do my tiller's tines turn but the wheels don't?

Main causes: clutch cable problems, faulty transmission…

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Why does my tiller turn the soil poorly?

Main causes: damaged tines, broken clevis pins, worn drive belt, faulty transmission, clutch cable problems, improper de…

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Why won't my tillers wheels or tines turn?

Main causes: worn or broken drive belts, bad transmission, clutch cable problems…

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Why does my tiller's engine leak oil or gas?

Main causes: leaky engine head gasket, damaged sump gasket, damaged oil drain plug seal, loose or cracked fuel line, lea…

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Why do my tiller's wheels turn but the tines don't?

Main causes: broken shaft clevis pins, transmission failure…

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Why does my tiller's engine run roughly or misfire?

Main causes: dirty carburetor, engine needs tune up, stale gas…

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Why won't my tiller's engine start?

Main causes: carburetor failure, bad gasoline, dirty spark plug, broken recoil starter…

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Most common repair guides to help fix your tillers

These step-by-step repair guides will help you safely fix what’s broken on your tiller.

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How to replace a tiller recoil starter

How to replace a tiller recoil starter

The recoil starter spins the engine when you pull the starter rope, and the rope retracts when released. If the recoil s…

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Repair difficulty
Time required
 15 minutes or less

Effective articles & videos to help repair your tillers

Use the advice and tips in these articles and videos to get the most out of your tiller.

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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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A guide to garden tillers

A guide to garden tillers

Rear tine tiller or front tine tiller, what to know to help in choosing the correct one for your needs.…

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