Hayward CAT 1000 pH controller problem

[eemueller]

I am unable to calibrate my CAT 1000. I have replaced the sensor with a new one, and I still have the issue. Water testing puts the pH at 7.8, but the CAT 100 reads 6.2. When I attempt to calibrate the unit, the light stays red and will not allow me to increase the value on the display. Any suggestions would be greatly appreciated.

 

[eemueller]

A follow up:
After changing the pH sensor, I still had the same problem. I contacted Hayward, and after trying the factory reset (twice), they didn't know what was wrong and suggested I send the unit in for a $500 repair. As I was looking things over, I noticed that the pressure switch in the return line was leaking through the switch. I replaced the switch ($40) and that solved the problem. I contacted Hayward and told them what I had found and they said they had never heard of this issue. Hopefully, they add this to their knowledge base.