dhindo

I was haveing problems with the 'NO FLOW' light staying on and I know there was water flowing through the system. I have replaced the NO FLOW switch and put on a new T-CELL as the old cell was just that 'old'. I am still having a problem with the 'NO FLOW' light. It still stays on. I have double checked the installation of the 'NO FLOW' switch and it is correct. The only other explanation I can come up with is that there is a problem in the circuit board. Any hints on how to check the circuit board?