Here's a thread on it:
http://www.atariage.com/forums/topic/142708-fine-tune-heavy-2600-picture-over-saturated-pic/page__view__findpost__p__1730311
Even has a picture of where it's located.
I just bought Kaboom and will be playing it for the first time when it arrives.
I also watched the Atari documentary with you in it; "Once Upon Atari" this past week. Thanks for everything!