Well, I now have nipple rotation. :crazy1:
Did it make any difference? I'm not sure. It does look just a touch bluer on the side of the tank where the bulbs needed to be rotated. Of course it's also possible I'm guilty of expectation bias, and I'm seeing what I want to see. I'll be curious to see if my wife can tell any difference when she gets home.
Tkeracer619, I ended up using your suggestion to bend the tab up. The bulb is a touch loose in the socket but there's obviously enough contact or the bulb wouldn't light.
Ganjero, when I had the bulb out I could see 4 small screws in the socket. Two obviously were to hold the socket to the L bracket in the back. The other two may well be to allow adjustment of the metal part within the socket. Next time I replace the bulbs I will take the fixture off the tank and experiment with them.
Thanks everyone for your help...and a little levity too!! :lol: