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DP
Treadmill

Model # 21-3900A Official DP treadmill

Here are the diagrams and repair parts for Official DP 21-3900A treadmill, as well as links to manuals and error code tables, if available.

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Model diagram and schematic

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ALL PARTS
Showing 10 of 73 parts  |
Lock Nut 25001500
#53

Control panel diagram

Lock nut

Part #25001500

The manufacturer no longer makes this part, and there's no substitute part

5/16 Locknut 25009800
#54

Motor and walking belt assembly diagram

5/16 locknut

Part #25009800

The manufacturer no longer makes this part, and there's no substitute part

Lynchpin 29431967
#15

Motor and walking belt assembly diagram

Lynchpin

Part #29431967

The manufacturer no longer makes this part, and there's no substitute part

Motor Cover 09154841
#19

Motor and walking belt assembly diagram

Motor cover

Part #09154841

The manufacturer no longer makes this part, and there's no substitute part

Screw 20013100
#35

Control panel diagram

Screw

Part #20013100

The manufacturer no longer makes this part, and there's no substitute part

Assy,front R 39330900
#22

Motor and walking belt assembly diagram

Assy,front r

Part #39330900

The manufacturer no longer makes this part, and there's no substitute part

Motor Mount 38338610
#27

Motor and walking belt assembly diagram

Motor mount

Part #38338610

The manufacturer no longer makes this part, and there's no substitute part

Exercise Equipment Reset Switch 37024500
#6E

Control panel diagram

Exercise equipment reset switch

Part #37024500

The manufacturer no longer makes this part, and there's no substitute part

Cap Foot 02007700
Cap foot

Part #02007700

The manufacturer no longer makes this part, and there's no substitute part

Console Assembly 39344000
#11

Control panel diagram

Console assembly

Part #39344000

The manufacturer no longer makes this part, and there's no substitute part

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…

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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…

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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'…

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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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