Mitsubishi Diamond Pro 2070SB Very Dim

[DUxPrime]

I recently picked up a Mitsubishi Diamond Pro 2070 VGA CRT monitor. When I brought it home, I was a little dismayed to see that it's quite dark despite both the contrast and brightness being at 100% and the "super bright" option enabled. I'm not able to see below the 20 on this black level test.

This is especially apparent in games with dimly lit areas:

There's also some brightness weirdness going on toward the right and left edges:

When I use the monitor's "constant brightness" feature (said to reset the monitor back to factory brightness based on its current state) to recalibrate, it reduced the brightness to 30% and was not usable. This suggests to me that the electron gun isn't strong enough to produce ideal brightness at factory levels.

The monitor has a reasonable number of active hours (around 12k on), so I wouldn't expect the tube to be wearing out just yet. Does anyone have any suggestions on what I can do to improve the brightness?

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I also noticed that there was a horizontal flickering line about an inch above the bottom right corner. I switched from using a GeForce RTX 3070 with DP-to-VGA adapter (StarTech DP2VGAHD20) to a VGA-capable capable graphics card (Radeon HD 5450), and the flickering has gone away. Does anyone know what might be going on there?

 

[DUxPrime]

Bump.

 

[tongshadow]

How many CRT Monitors have you owned? Is this dimmer than them?

 

[DUxPrime]

How many CRT Monitors have you owned? Is this dimmer than them?

This is the first VGA monitor I've owned in a while, but I've owned several PVMs/BVMs. The thing that mostly has me concerned is how poorly it does in the black levels test.

 

[tongshadow]

This has worn tube written all over it, but 12k is nothing for a CRT. Try readjusting the G2 pot on the flyback and see if black levels improve.