dose a crack in a single end bulb effect the bulb or dose the outside glass just as a uv sheld. I have a ushio 10k 2Mo.old hamilton 10k 3mo. old hamilton 14k 3 days old. they are all cracked the ushio was cracked for a couple of days before I noticed. now on my nano I have some no name bulb that seems very dim. would I be better off putting one of the cracked bulbs back in?