Need help tuning Epson 14" CRT based VGA monitor

[1200XL M.U.L.E.]

I just got an Epson 14" CRT based VGA monitor. The model number is A804031. I connected it to my Epson Equity I+ machine which has a VGA card in it. An image comes up and is only a little soft ... but sharp enough. The problem is the background looks like the brightness is turned up too high. It's almost grey. I tried turning the brightness down all the way but it's not enough.

I searched for "epson a804031" hoping to find a service manual or some forum posts about this but nothing came up.

When I turned on the monitor without any input connected to it I heard a sharp click, as if something arced inside. Maybe the monitor wasn't turned on for a long time and a capacitor needed charging? With the computer on and the monitor showing an image, the monitor would make a quieter and softer clicking noise and the image would jump with each click. The clicking and jumping went away after a few minutes. Maybe this was like a burn-in phase?

Can anyone here offer some help on how to tune down the brightness so I have a crisper image?

Thanks!

P.S. Edit - I am attaching an image of what the background looks like.