Years ago we had to replace the top part with the solenoid in it as the solenoid was open circuit, see link to 495 Ether Starting.
On the 574 parts manual it showed the ether starting solenoid by the part number referred to a link that didn't work so went to 495 a newer model that gave part number 87105749 for the solenoid.
If you Google 87105749 you will see several different vendors. I sort of remember that the solenoid on ours wasn't replaceable and had to replace the complete top assembly but I do believe the replacement part the solenoid is replaceable.
IIR correctly there are 2 wire: -12V with Generator, +12V with Alternator and Ground also can't remember if push button switch on the dash supplies voltage or ground to the Ether solenoid.
I will not get involved in the Ether starting discussion, there are some simple rules to avoid damage to the engine.