Polti Vaporetto steam cleaner- can't stop flow of steam from machine?

In short I did this:

Add 3 vials of calstop in tank
Heat up machine
Keep pressing the hose steam control button on and off to let the calstop run through the solenoid valve

spik and span
August 2018

UPDATE

I suspected that the solenoid valve was stuck open (my steamer had been in storage for a while). I used extra calstop in tank during use. Later I was just using the on/off button on the hose and noticed the clicking noise on the machine appeared to get louder. I kept switching the steam control on and off and eventually the solenoid valve became unstuck and I could control the steam with the on and off button. Yippee

spik and span
August 2018