Sparky, I had a similar problem with a similar contactor.
The close coil was burning out, It had voltage all the time when the contactor was not energized.
Same set-up as yours, photo cell to control relay, to contactor.
The problem was a aux contact on the contactor that feeds the close coil. This contact was not opening when the contactor shut off.
But if you change the whole contactor as one unit, I doubt this would be your problem.
Just thought I through it out there, it took 2 close coils to find it, as the aux contact wouldn't stick all the time.
