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  |

5/16 Locknut 25009800
5/16 locknut

Part #25009800

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

Lock Nut 25001500
#51

Figure 1 diagram

Lock nut

Part #25001500

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

Treadmill Owner's Manual 60102800

#NI

All parts diagram

Treadmill owner's manual

Part #60102800

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

Bolt 22015500
#43

Figure 2 diagram

Bolt

Part #22015500

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

L Foot Cover 09145300
#25

Figure 2 diagram

L foot cover

Part #09145300

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

Front Leg 38334916
#16

Figure 2 diagram

Front leg

Part #38334916

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

Rear Roller 39311600
#21

Figure 2 diagram

Rear roller

Part #39311600

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

Handrail As 39335800
#9

Figure 2 diagram

Handrail as

Part #39335800

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

Cntrllr Brkt 31279810
#29

Figure 2 diagram

Cntrllr brkt

Part #31279810

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.…