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Horizon
Treadmill

Model # QUANTUM II Official Horizon treadmill

Here are the diagrams and repair parts for Official Horizon QUANTUM-II treadmill, 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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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 143 parts  |
Breaker MC0702011
#P04

Treadmill assembly 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
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
Back Order
Rail Lock MB0643001
#Q10

Treadmill assembly diagram

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
Washer MZE0505033
#B65

Treadmill assembly diagram

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
Cable MC0503001B
#P08

Treadmill assembly diagram

Cable

Part #MC0503001B

Replaced by #002124-B

?
Manufacturer substitution
This part replaces MC0503001B. Substitute parts can look different from the original.
This item is not returnable
$4.47
In Stock
T-wrench MZE1002003

#NI04

All parts diagram

T-wrench

Part #MZE1002003

Replaced by #005393-00

?
Manufacturer substitution
This part replaces MZE1002003. Substitute parts can look different from the original.
$8.50
In Stock
Spring MZE1103001
#L15

Treadmill assembly diagram

Spring

Part #MZE1103001

Replaced by #005438-00

?
Manufacturer substitution
This part replaces MZE1103001. Substitute parts can look different from the original.
This item is not returnable
$2.16
In Stock
Cable MC0501029E
#P06

Treadmill assembly diagram

Cable

Part #MC0501029E

Replaced by #002027-A

?
Manufacturer substitution
This part replaces MC0501029E. Substitute parts can look different from the original.
$22.67
In Stock
Bolt MZE0121003
Bolt

Part #MZE0121003

Replaced by #004864-00

?
Manufacturer substitution
This part replaces MZE0121003. Substitute parts can look different from the original.
This item is not returnable
$2.79
In Stock
Nut MZE0204013
#M12

Treadmill assembly diagram

Nut

Part #MZE0204013

Replaced by #004934-00

?
Manufacturer substitution
This part replaces MZE0204013. Substitute parts can look different from the original.
This item is not returnable
$2.26
In Stock

Symptoms for treadmills

Choose a symptom to see related treadmill repairs.

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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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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 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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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 walking belt

How to replace a treadmill walking belt

A worn walking belt will begin to slow down during use. If your treadmill walking belt is worn out, replace it using the…

Read more
Repair difficulty
Time required
 45 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

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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