E1 indicates a possible problem with the speed sensor, near the motor. You will need to check the speed sensor for proper alignment, cleanliness and function. It should be located near the front roller or mounted on the motor. It should be within a credit cards width of the magnet or toothed wheel. If it is properly adjusted then test with a multi-meter to see if it is opening and closing correctly by manually spinning the front roller or motor flywheel. If the sensor is not responding when tested then it will need to be replaced.
Ok, then something is causing the belt to drag - has the machine been serviced recently?
If the belt is worn underneath, it will need to be replaced.
Have you tried applying some belt lubricant to the underside of the belt?
Ok one more test - remove the belt completely from the motor and check if it turns on its own;
if it will still not turn unassisted then the motor has a fault and will need to be replaced.