Response from Jonathan: Josh,

Yep, probably time to start looking at the flyback. Make sure that you try adjusting the brightness on the flyback as well before you replace it. If the screen continues to be dim after replacing the flyback, it’s possible that you could have an issue with your tube. You can try using a tube rejuvenator on it at this point. If the tube rejuvenation doesn’t fix the brightness issue, then you will either need to find a replacement tube that’s compatible with your chassis or replace the monitor entirely. Hope that helps.