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Your ozone unit is simply a light that the air goes through...the tub itself has a venturi line built in somewhere that creates air flow. You must find the reason it is not sucking air. With the system running, take off the in line check valve and see if it sucks air, make sure you did not install the check valve backwards. Without airflow, ozone unit is useless.
What the tech told you is true. There's unlikely anything wrong with the ozonztor. The ozonator does NOT produce any bubbles. It is simply a box, with a UV light bulb in it. Other aspects of the spa draw air through the box, where some of the O2 in the air is converted to O3, and drawn into the water. Think of it this way. Blow through a straw. Air comes out the end of the straw. Stop blowing. Now no air is coming out of the straw. Is the straw broken?