Oh, ok. So that built-up crusty stuff that looks like asbestos can go? I can rub it off with my fingers.
Yeah. That's just crud and dust that got attracted to the tube from static. The aquadag coating is under that, it looks a bit like dark grey spray paint. It's on there pretty good, but serious scrubbing will take it off.
My procedure for cleaning nasty monitors is:
-Disconnect and remove chassis
-put duct tape over the anode connection on the picture tube (reduces the amount of water that gets in there, don't want the connection to corrode)
-spray back of the tube with Simple Green, let it sit for a minute, then wash it off with the hose
- let the tube sit and dry, you can remove the tape before it bakes to the glass
- after the tube is dry, clean the area right around the anode connection with alcohol or Windex, to ensure it's really clean. Crud here can cause a discharge path.
Similarly, I'll hose down the chassis quick too. This gets the majority of the crud off. Then put it in the dishwasher (top rack, coil up the wires so they don't get caught in anything), and clean with usual dish soap, no heated dry. After that's done, shake out as much water as you can. Set the oven to 150/175 (basically, as low as it will go), and put the chassis on a foil-covered cookie sheet. Let it "bake" for a half hour/45 minutes or so, until it's nice and dry.
You probably don't want to run dishes through along with a monitor chassis. I have put various monitors through the dishwasher over the years, primarily G07's and 4900's. Obviously, clean them, then recap/rebuild. If the width coil on a G07 isn't broken already, might want to desolder it first - they're pretty brittle. If the monitor isn't that dirty, washing it probably isn't worth the effort, I've only done it on ones that were so filthy I couldn't see the components on the board. It's very hard to rebuild/recap a monitor that dirty.
-Ian