TOMB, I have the black plastic disk (it's just below the semi-transparent disk I'm holding) between the hand grip and the throttle body. From my pre-restoration pictures this looks correct. Looks right from my Barber Le Mans pics as well. It's the large semi-transparent one that is a mystery. I'm fairly confident it was part of the throttle/grip assembly, and it has witness marks on it that appear to line up with things.
Steve, I just sprayed a lot of Slick 50 One Lube inside and all around it so maybe that'll help. I lost the tiny rubber pad somewhere along the way... one of a just a couple parts that went missing, don't ever use the cruise control anyway.