The E7 error code indicates a fault with the motor.
The best way to test the motor is to apply external power to the motor and see if it runs ok.
If it is still making a loud buzzing noise when external power is applied to it then this confirms it is faulty and will need to be replaced.
yes, dust can prevent the motor from working.
Give it a good clean first, and if it still doesn't work, then test the motor.
The E7 error code indicates a fault with the incline motor.
If the motor only runs for a few seconds when testing it with an external power source, then this confirms that the motor is faulty.