Don’t know much about the guts of a steam cleaner, but I wonder if
they are like household hot water heaters. If you turn those on when
there’s not enough water to cover the heating element, they burn out
immediately. I learned that the hard way. Maybe your water level
guage is not showing you the true picture, for some reason. And you
want to make sure those valves top and bottom of the glass are open.
Please forgive me if I’m pointing out the obvious, or things you’ve
already thought of, it’s just that in 27 years of using steamers,
I’ve never had to replace an element.