Weird discoloration on Color Classic CRT

[wottle]

I picked up a non-working CC a while back and just last night I tracked down the failure to boot to be from two failed vias by a leaky capacitor. Once I got the bodge wires hooked up to correct spots, I was able to get the machine to boot up. Fortunately, even the original HD was still working.
Oddly, the CRT seems to have a discolored area in the middle. I’ve never seen it before on any of my CRTs.



It’s definitely not on the exterior glass surface. It also doesn’t seem to move at all or change with the image behind it changing.

I don’t feel like I’m hearing the “thunk” of the degauss circuit doing its thing. Is it possible the degauss is bad and this is a symptom of it needing to be degaussed after sitting for years? Or could the unit have been stored face down and contaminants settled on the front of the phosphor coating, causing this?

Anyone seen anything like this before?

 

[wottle]

So, probably not the best idea, but wanted to see if it was a magnetization issue, so I took some magnets and moved it around by the screen and the dark spots definitely shift and move. Unfortunately, they are now worse than they were before. I assume that means it is likely an issue that degaussing will resolve / help lessen. And the lack of the degaussing sound means my degaussing coil isn't being active on startup. I plan to disassemble and clean everything, as well as inspect the caps on the analog board and replace any that look problematic. While I'm in there, I can see if anything looks bad or if the degauss coil is properly connected.

Anyone have experience with the cheap degaussing wands on Amazon? It seems like it's that or a $100+ hoop degausser. If I can get away with the little wand ones taking longer to remove the magnetic field, I'd rather save some money to not buy something I will likely never use again.