Up until a week ago, our lamppost was working fine with its dusk to dawn photo sensor. First I changed the bulbs with bulbs I knew were working - nothing. The power connection seems to be fine. In fact after a week of not seeing the lamp on during my normal waking hours while dark out, I noticed it was on at 6:30 am this morning (a rare early morning for me). This leads me to believe it's somehow 'off'. Is this a normal situation when the sensor starts to go?

Is my only option replacing the sensor and hoping it works? Or is there something I'm missing?