You need a better method of testing.

http://www.troublefreepool.com/pool-school/pool_test_kit_comparison

Has this ever been resolved satisfactorily by Pentair? I am having the same problem and the same runaround with an IC40 cell blinking even though the cell is only two years old and has been cleaned and indicates life at 60%. I'm at a point where I'd like to replace everything Pentair but of course that would be cost prohibitive.

What are your water chem readings? phosphates does play a role in the voltage pull. Has anyone done the bucket test?

Steps, (Dont tell Pentair you did this)

1) take a 5gal bucket of your pool water.
2) Drop the cell in it
3) Drop a golf ball or something in the cell to close the flow switch
4) wait two mins and be sure the output is at 100%
5) did it bubble?

Chances are it did and if thats true then its a water issue. This is the fastest way to check the cell.