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  |

Washer 26000400
Washer

Part #26000400

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

Screw 20016000
Screw

Part #20016000

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

Lock Nut 25001500
#53

Control panel diagram

Lock nut

Part #25001500

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

Lock Nut 25011100
Lock nut

Part #25011100

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

Washer 26006300
#50

Motor and walking belt assembly diagram

Washer

Part #26006300

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

Washer 26000667
Washer

Part #26000667

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

Adj Foot As 39337400
#17

Motor and walking belt assembly diagram

Adj foot as

Part #39337400

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

Monitor 37036800
#3

Control panel diagram

Monitor

Part #37036800

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

Symptoms for treadmills

Choose a symptom to see related treadmill repairs.

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

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

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

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

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

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

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

Repair guides for treadmills

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

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…

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…

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'…

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.

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.…