I have a Milwaukee Instruments MA957 that I have been using for over a year. For the last few weeks, the bubbles have been harder to come by meaning that I leave the fine needle value open all the way and just use the large knob as the bubble rate diffuser. There are no bubbles has gas out at all in the counter. I called the company on Friday and they suggested removing the clear chamber and use a pencil lead drill bit to break up the clog that she suspected had happened causing no gas excaping. I did that several times and it still does not work. I am going to call them again on Monday and see about sending to them to repair.