Below are photos showing how to check and take apart a steam fill solenoid valve on an M58 or Vetrano 2B. If one of these machines has flow through the group head but the pump constantly runs, attempting to refill the steam boiler, then the first suspect is a bad steam fill solenoid valve. Before attempting to check the solenoid valve you will want to unplug your machine from the wall and allow it to fully cool off. You will also need to remove the side panels which is detailed here.
- 17mm deep socket & socket wrench
- vice grip / adjustable wrench
"Check for flow through the hole by turning machine on and running pump. Be sure to cover the hole as it will spray water when the pump is ran. Also, be sure that the black solenoid coil wires aren’t exposed and touching any other parts"
If the solenoid valve body sprays water when the pump is running the then black solenoid box and the metallic solenoid shaft likely need to be replaced. You can test if water runs through it by lifting the brew lever with the solenoid off of the body.