Q - When do I know the solenoid valve needs replacement?
A - When the airflow will not stop and you are unable to re-light your plasma cutter.
Q - Is this a difficult part to replace?
A - It will take some technical ability, but there is information in the manual on how to replace this part.
Q - Does this work with the whole Powermax line?
A - No, it is designed for the Powermax 65 or 85.