This thing is hit and miss. When it chooses to work, it works well. That, however is rare. Have read the manual and gone online for some trouble shooting, to no avail. None of the suggestions have worked. Maybe the model with the reservoir would work better.
The price was just right. I wasn't sure if it was worth the money to buy the larger size. This model turned out to be perfect. The water reservoir seems small, but fill it once for the bottom teeth and once for the top teeth. You will feel the difference on your teeth right away. Stays charged for a long time.
I already have the WP-900 for home use and wanted a unit for vacation. The WP-360 seems to bit that need. It is powerful enough and as small as it can be and still hold a sufficient amount of water. It is little hard to maneuver around your mouth compared to the 900 but with little practice it can be done.