[old_tv_nut]

I'm guessing now that L18 is supposed to be self-resonant at 3.58 MHz, and the purpose of setting L19 to minimum at 3.58 MHz is to flatten that peak. So, it looks to me like L18 is tuned to too high a frequency. When you turn the color level, the peak should go up and down at 3.58 MHz, not at the higher frequency shown.