Is it the built in one or the inline one?
I have the built in one and it requires, first of all, the water temp to
have reached maximum, then switch pump on, put on full revs and
switch over to Steamate then wait for red light to go out.
Mine is the 400psi model.
Mine packed in after 13 months, just out of warranty

, and to get
it fixed locally was estimated around £170

Needless to say I didn't bother and to be honest 2 years down the
line I don't miss it.
If you have a good in tank heater that will more than suffice.
John