Can’t find your part?   Contact us:
+1-309-603-4777
Sears Parts Direct
Orders

  • Keep track of the models you own in your profile

    Sign in or Register to view or add models

Schedule a repair
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.

There are a couple of ways to find the part or diagram you need:

  • Click a diagram to see the parts shown on that diagram.
  • 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”.

We encourage you to save the model to your profile, so it’s easy to access parts and manuals for your appliance whenever you log in.

For DIY troubleshooting advice and repair guides, visit our repair help section.

Model diagram and schematic

SEARCH WITHIN THIS MODEL

?

This is the number corresponding to the part on the diagram / schematic

Search
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

Spd Cntr Knb 39344200
#11D

Control panel diagram

Spd cntr knb

Part #39344200

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

Washer 26002200
Washer

Part #26002200

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

Handrail As 39335800
#9

Motor and walking belt assembly diagram

Handrail as

Part #39335800

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

R End Cover 09118500
#24

Motor and walking belt assembly diagram

R end cover

Part #09118500

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

Front Leg 38334916
#16

Motor and walking belt assembly diagram

Front leg

Part #38334916

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

Flywhl Pully 39262900
#29

Motor and walking belt assembly diagram

Flywhl pully

Part #39262900

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

Lock Washer 26009700

#NI

All parts diagram

Lock washer

Part #26009700

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

Symptoms for treadmills

Choose a symptom to see related treadmill repairs.

View all

Why does my treadmill's walking belt slow down?

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

Read more

Why is my treadmill's walking belt slipping?

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

Read more

Why is my treadmill's walking belt off center?

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

Read more

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…

Read more

Why is my treadmill's heart rate sensor not accurate?

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

Read more

Why does my treadmill have no display?

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

Read more

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…

Read more

Repair guides for treadmills

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

View all
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 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
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…

Read more
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.

View all
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.…

Read more

Parts & More