To adjust the luminance pots, I used the 7800 cart Ballblazer. Turn 2600 pot to max resistance, and adjust 7800 pot to suit. Then, turn 2600 pot to full, and slowly turn down until the flickering lines disappear. The background in Ballblazer shows the flickering more prominently than the other games that I tried. Once the flickering is no longer noticeable, you're finished (but do try out a 2600 cart to be sure).