DP
Treadmill

Model # 21-3900 Official DP treadmill

Here are the diagrams and repair parts for Official DP 21-3900 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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Showing 10 of 76 parts  |

Motor 37035400
#27B

Figure 2 diagram

Motor

Part #37035400

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

Handrail 30446116
#9A

Figure 2 diagram

Handrail

Part #30446116

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

Lock Nut 25021200
#11I

Figure 1 diagram

Lock nut

Part #25021200

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

Washer 26000400
Washer

Part #26000400

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

Screw 20013100
#33

Figure 1 diagram

Screw

Part #20013100

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

Bellows 09104600
#8

Figure 1 diagram

Bellows

Part #09104600

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

Adj Foot As 39349200
#17

Figure 2 diagram

Adj foot as

Part #39349200

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

Potentiometer 37027800
#11C

Figure 1 diagram

Potentiometer

Part #37027800

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

Frame 30439116
#18

Figure 1 diagram

Frame

Part #30439116

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

R Foot Cover 09145400
#24

Figure 2 diagram

R foot cover

Part #09145400

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

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

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

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 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
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…

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.

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.…