Since the amps are ok, I suspect that everything is ok. However, I would like to know what Zodiac says.
Dear,
If you have an occassional "Output Fault" message showing on the display and the fan sometimes fails, it means that the power supply pcb may be on its way out. If you are still able to use the unit, just observe from time to time your chlorine levels.
With regards to the voltage output on the cell, it should be around the 20V range but the most important factor there is that you are getting 7.2A output. That means the cell will be producing the correct current to produce the chlorine.
Perhaps the connector has a high resistance and causes a voltage drop when plugged together. Can you clean the connector and assemble with dielectric silicon grease.