you can leave it at 1k but you chance burning the image into your tube (static things like "insert coin" messages etc.) you can leave it there, but turn down your brightness and contrast a little.
don't forget this is a crt monitor...not a super bright plasma display with a billion to 1 contrast ratio. your vision has been sullied by high definition. 
Thanks, I have contrast almost all the way and brightness. Does it matter if is like that. I like how vivid the games look and sharp. So It would safer to turn down the contrast and brightness more.
I'm not going to hold you back...you can crank that thing up as bright as you want and have it look how you like, i'm just warning you, really bright graphics can be burnt into your screen if they get left on for long periods of time. You can reduce this chance by toning things down a little.
with lcd and plasma display having become dominant, crt tubes aren't a dime a dozen anymore. You will come to the realization one day that you need a new tube or monitor and there won't be any left. Sad to say, it's pretty much here and now. It's best to hold on to what you have and keep it as long as you can.
Who knows, one day in the far future you could sell that monitor for $5000 to a guy trying to restore his big buck hunter.
