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Horizon
Treadmill

Model # 5.1T Official Horizon treadmill

Here are the diagrams and repair parts for Official Horizon 51T treadmill, 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.

Model diagram and schematic

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ALL PARTS
Showing 10 of 162 parts  |
Socket MC0703023
#P11

Treadmill diagram

Socket

Part #MC0703023

Replaced by #019749-A

?
Manufacturer substitution
This part replaces MC0703023. Substitute parts can look different from the original.
This item is not returnable
$9.62 | 
9% OFF Phone Price : $10.62
In Stock
Nut MZE0204005
Nut

Part #MZE0204005

Replaced by #004926-00

?
Manufacturer substitution
This part replaces MZE0204005. Substitute parts can look different from the original.
This item is not returnable
$2.16
In Stock
Breaker MC0702011
#P04

Treadmill diagram

Breaker

Part #MC0702011

Replaced by #003346-00

?
Manufacturer substitution
This part replaces MC0702011. Substitute parts can look different from the original.
$14.80
In Stock
Bolt ME0104098
#R04

Treadmill diagram

Bolt

Part #ME0104098

Replaced by #004496-00

?
Manufacturer substitution
This part replaces ME0104098. Substitute parts can look different from the original.
This item is not returnable
$5.57
In Stock
Washer MZE0505033
Washer

Part #MZE0505033

Replaced by #005196-00

?
Manufacturer substitution
This part replaces MZE0505033. Substitute parts can look different from the original.
This item is not returnable
$2.26
In Stock
Rail Lock MB0643001
Rail lock

Part #MB0643001

Replaced by #001251-F

?
Manufacturer substitution
This part replaces MB0643001. Substitute parts can look different from the original.
This item is not returnable
$3.92
In Stock
Console Cable MC0502044A
#P06

Treadmill diagram

Console cable

Part #MC0502044A

Replaced by #002103-A

?
Manufacturer substitution
This part replaces MC0502044A. Substitute parts can look different from the original.
$25.94
In Stock
Bottom Cover MB0237017AA
#Q05

Treadmill diagram

Bottom cover

Part #MB0237017AA

Replaced by #000382-AA

?
Manufacturer substitution
This part replaces MB0237017AA. Substitute parts can look different from the original.
$19.94
In Stock
Screw MZE0121004
#Q19

Treadmill diagram

Screw

Part #MZE0121004

Replaced by #004865-00

?
Manufacturer substitution
This part replaces MZE0121004. Substitute parts can look different from the original.
This item is not returnable
$2.16
In Stock
Safety Key MR0004003A
Safety key

Part #MR0004003A

Replaced by #051345-A

?
Manufacturer substitution
This part replaces MR0004003A. Substitute parts can look different from the original.
This item is not returnable
$30.87 | 
16% OFF Phone Price : $36.87
In Stock

Symptoms for treadmills

Choose a symptom to see related treadmill repairs.

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Why does my treadmill's walking belt slow down?

Main causes: damaged walking belt, improper belt tension, lack of belt lubricant, bad drive motor…

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Why is my treadmill's walking belt slipping?

Main causes: damaged walking belt, improper belt tension, bad roller bearing…

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Why is my treadmill's walking belt off center?

Main causes: rear roller out of alignment, damaged walking belt, bad roller…

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Why won't my treadmill start even though the console display works?

Main causes: missing safety key, bad control console, wiring failure, faulty motor control board, bad drive motor…

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Why is my treadmill's heart rate sensor not accurate?

Main causes: faulty sensors, wiring failure, bad control console…

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Why does my treadmill have no display?

Main causes: bad control console, wiring failure, bad motor control board…

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Why won't my treadmill power up?

Main causes: no power, bad power cord, tripped or faulty overload switch, bad power switch, wiring failure, bad motor co…

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Repair guides for treadmills

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

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How to replace a treadmill motor controller

How to replace a treadmill motor controller

Your treadmill motor won't run with a defective motor controller. Replace the motor controller if it doesn't operate the…

Read more
Repair difficulty
Time required
 15 minutes or less
How to replace a treadmill drive motor

How to replace a treadmill drive motor

A defective drive motor won't run when activated by the motor controller. Replace the treadmill drive motor if it doesn'…

Read more
Repair difficulty
Time required
 15 minutes or less
How to replace a treadmill walking board

How to replace a treadmill walking board

A worn-out walking board creates friction with the walking belt and causes the belt to slow down during use. Replace the…

Read more
Repair difficulty
Time required
 30 minutes or less

Effective articles & videos to help repair your fitness & exercise

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

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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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