The user above is correct. And the steps to correct it: The thumb trigger and the sliding brass valve clog up and dont move. So if you use it and press the thumb trigger and no steam comes out, it's probably clogged.
Wait until it cools down. Empty the unit.
1.) unscrew any attachments and you will see where they screw in at the end, two small philips head screws on the end. remove them. The red rounded piece at the end will come off.
2.) now on the top, unscrew the water stopper top where you poor water in.
3.) Now below that is a round rubber piece that surrounds the threaded part where the stopper top screws on to. Grab it with your fingers and lift it up on the sides to remove it.
4.) now underneath here you can see two screws. Remove them.
5.) now grab the whole top piece that is "black" and pull upward to remove it. you may want to start at the front and work it off. It has a few snaps that will release when pulled. I have done this a few times so dont be afraid to pull this piece off.
6.) now you will see the valve assembly. Take a small hammer and tap on the small rounded "brass" nub that is sticking out of the "trigger side" of the valve. To know if it has released, I usually place my lips around the end that the steam comes out of and blow while pressing in on the little brass nub on the other side. I do this until that nub moves freely and I can hear the air escape out the top from my blowing on it. Sounds funny but it works. If not free, tap it harder, a few more times, until it is free. It will free up eventually. It gets stuck from time to time but this will get you back in business fairly quickly.
7.) move the nub a few times to ensure smooth movement.
Re-assembly
1.) The black plastic top will snap into place. Just line up the trigger spring with the red nub and snap the whole black piece back into place.
2.) place the two screws back in.
3.) The rubber protector ring is tricky. You will see the underside has a rubber edge that snaps in place. Work it around as best as possible and i usually use a screw driver to push the last little bit into place.
4.) place the red circular end cap on and the two screws that go with it.
you are all done. Once you do this a few times, you will become a pro OR as the above poster said, use distilled water.
JM, February 2008