We have a GC20SC-5 and it has a hard time starting. It will start on starting fluid and run. Once you turn it off it will have a hard time starting again. You can also disconnect the vacuum line going from the mixer to the regulator and blow/suck into the line to activate the diaphragm in the regulator to get it to start. The machine has no codes and it seems to be a vacuum problem not allowing the diaphragm to work properly. Any help would be very appreciated. Thank you in advance.