Hi Mike
The only things that will give you an E error is the motor or most of the time the micro switch.
First, make sure that the wires to the switch are connected and firmly seated into the connector. Take the connection apart and check the pins inside the connector for corrosion.
Secondly make sure nothing is blocking that switch and the motor arm.
The motor should stop when the brass arms on the motor depress the black button on the switch.
If the motor continues to advance the motor needs to be moved closer to the switch by losing the two mounting screws and moving the motor closer to the switch we are taking fraction of an inch here.
If the motor continues to turn you have a defective Internal Advance Switch
The switch is not to hard to change you just need a pair of real small hands.

Brian.