You may want to check that "intensify pulse" thing and circuitry to be sure it's working right. I don't recall if it should be active except in pulse mode. Speaking of which, are you sure you have the controls set up properly? Make sure it's not in pulse mode - there are buttons to select these, but I'm nowhere near a 576 right now, and can't see a panel to refresh my memory, so can't describe the right settings. You'll want it to be set for "normal" or "repetitive" or something like that.
If you figure out all the right operation, and the CRT is indeed very dim, it may be a candidate for rejuvenation, or replacement.
Ed
