Why Is My Treadmill Slowing Down? Reasons and Solutions

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If your treadmill runs properly when switched on and slows down as soon as you step on it, it is not operating normally. Sometimes, it also begins to slow down suddenly after a little time you start working out, even though it was working fine initially.

When this happens, there are four reasons you need to consider about your treadmill.

  • 85% of the time, the walking belt or the deck are worn.
  • 8% of the time, the motor belt or the walking belt are too tight, especially if you have adjusted it recently.
  • 5% of the time, either the motor has demagnetized or has lost torque and requires brushes.
  • 2% of the time, it’s the dropping out of the controller.

Worn walking belt

You can verify the deterioration of the walking belt by taking the AC amp draw if you have an AC motor or a DC draw if you have a DC motor. It is the only certain way today to determine how worn is the walking belt. It is not appropriate to understand the condition of the belt using a feel test and is unreliable.

If you do not possess a DC ammeter, you can try an Incline test or a Coast test. The deck inspections instructions are provided in the troubleshooting section. All you need to do is to download these instructions and test the deck.

Coming to the Coast test, you can set your treadmill to its lowest in incline settings and start walking on it at a speed of 3 MPH. While doing so, pull the safety key and observe the number of steps you take before the treadmill stops.

If you take only two to three full steps before your treadmill comes to a stop, then your belt is fine. This general rule helps you learn the friction of the belt with the roller. Some models stop Immediately, indicating higher friction, but it still indicates a healthy belt.

If it is anything more than that, then you should consider checking your belt more thoroughly. Similarly, an Incline test requires you to put the treadmill on its maximum incline setting and walk at 3 MPH speed.

If the treadmill works fine on the maximum incline setting and slows down when on a minimum incline, it is time to change the walking belt. Here you are testing the drive system and the interaction of the walking belt with it.

When you put the treadmill on maximum setting, the gravity force is less on the belt than at a minimum incline, meaning it is not affected by the friction. On the contrary, if the walking belt is heavily worn, you cannot identify it using this test.

Belts too tight

If you have made any recent adjustments to your motor belt or the walking belt, check if it is too tight to move properly. Few individuals tighten the belt when it starts slipping by cranking it down and believe it to be a simple and effective process to fix this treadmill issue.

It is ineffective because if the belt is tighter than it should be, the drive system requires more effort to roll the treadmill belt. The best test to check if the treadmill belt is too tight is to lift it in the center of the belt up to three inches without much strain.

Of course, you need to do it after unplugging the treadmill. If you cannot lift it as indicated, you should loosen the belt till it satisfies the criteria. If you loosen it too much, there are chances of slipping and falling from the treadmill.

When you check the motor belt, again making sure the treadmill is unplugged, you should be able to turn the belt to an almost 90-degree angle using your hand from its normal position. If you cannot do as suggested, then loosen the belt as it is too tight.

After making adjustments check if the belt is slipping and adjust it further for proper tension, still, if you cannot achieve the right tension despite adjustment, then it is time to replace it.

Motor need brushes or is demagnetized

The motor might lose torque sometimes, meaning you need to replace its brushes with a new set. Another uncommon issue you can find with motor is demagnetization which is easy to recognize.

Once you make sure that the deck or belt is not worn and that both the belts are not too tight, the motor is tested for the torque issue. Never try to use your hand or any other body part to interfere with the motor when you are not sure the motor is working properly or not.

If it is working properly and you use your hand, then the chances are it might get stuck in the motor.

Using a long shaft or something similar, try to apply downward pressure in the same direction as the flywheel motion.

You can see the directional movement indicated on the motor tag if you are unsure which flywheel is moving. Do not attempt to obstruct the motor in the opposite direction as it can lead to injury.

If the motor slows down while applying pressure on the motor, as explained, then you do need to replace the brush. Disassemble the motor to test for demagnetization. Remove the bolts retaining the motor, then try sliding the motor core out from the end of the housing.

The magnets should attract the core and make it difficult to pull it out of the housing if they are good. Else if the motor slides out easily, then you should replace the motor.


If your controller is out of order, then your belt will not move properly with or without a person on it.

You will rarely face issues with a controller, and you can diagnose it by eliminating the other possible issues mentioned above.

If you see a drop in the DC output during the test, it is because the controls have a current limiter to prevent burning up the board by automatically dropping output. When it happens, along with eliminating the other causes, you might need to replace the controller as well as the belt.

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