Looks like strong bleed between colors. There is no contrast pot on the EZ20, so you'll need to adjust the screen knob on the flyback, and the drive pots on the neckboard for red & blue (there is no green pot). If adjusting the drive pots didn't seem to help with the bleed, then the screen knob on the flyback is probably a bit high (or it could be a combination of both).
How does the monitor look with your DK board? I ask because usually with Nintendo boards vs. TPG, the video signal voltage is higher for the actual game boards. So if the monitor was dialed in for DK, the TPG video will appear darker. In this case, the TPG output is really bright, which makes me think the flyback/rgb drive settings are too high.
Buffett might chime in if the B+ should also be checked. He is our resident EZ-20 enthusiast who uses the monitor in a lot of non-Nintendo games.