Sony SL-5800 Betamax - slow motion flicker adjustment?

[probnot]

Anyone familiar with something called the "brightness balance" on the Sony SL-5800? It appears to adjust the brightness between the two video fields during pause/slow motion/betascan, to eliminate flicker.

My problem is that it doesn't fully eliminate the flicker between the fields, and I found an old Popular Electronics article (attached) which mentions internal adjustments that are used to align it. I just have no idea what they are called and don't want to start guessing and blindly adjusting things since everything else on this VCR is working fine.