I have one of those Mercury Vapor yard lights. Normally when the bulb
burns out it starts getting dim and tends to go one and off. This
time it just stopped working. I went up and replaced the bulb and
noticed the socket had some black staining on it. The fixture should
not be leaking water. Of course anything is possible. I am
considering that dust and stuff combined with moisture could cause
this too, however I do not recall seeing this in the past.
With the new bulb, it still does not work. This makes me wonder if
it's the sensor or could the ballast have gone bad and that's the
black stain? I realize no one can answer this for sure, but has
anyone ever seen a ballast die, and does it leave a stain on the
socket? I suppose I got to take the whole fixture down, and working
on poles is not my idea of fun....