Swimming pools blog

Hi
With a meter:
I have a Pentair Amerlite Underwater Light, 12 volt, 300 watts that has
stopped working.
I have tested the voltage from the transformer to the junction box.
Test OK..
I have tested wires resistance from the ends to the bulb socket. Test
OK..
I have tested from the wires connected at the junction box from the
transformer to the bulb socket. Test OK.
I have tested the bulb. Test OK.
When all connected and assembled. . .will not work.
The only other testing that I think I could perform is to get another 12
volt bulb to see if that works in the socket or wire the blub to a 12
volt battery to see if the bulb works.

Please advise before I pop for a whole new fixture.
Thanks