Regarding the Tron disk/disks, I think you will find that the two rubber stickers are each placed on two disks (a circle spinning one way, within an outer ring spinning the opposite way). The reason you see the two red light circles on Tron, is that one red light is coming out of the gap between the inner circle and the outer ring, and the other red light is coming out from the out edge of the outer ring. Does anyone have a Tron to confirm it has one or two spinning disks?
Yes I do in my games room actually .. 
Have a look at the picture below to so see what is under Gene. There is a narrowing space beyond the spinning disk. I think is a ball capture hole is at the end of it for the locked ball.
Thinking of whether Gene's head lowers, yes it does look as if it may rotate forwards to lower the tongue. Looking at it now, the head does seem elongated back. That may be to avoid the head hitting the rails when it is rotated forward on ball launch. Have a look at a top view - I don't think it will hit the rail.
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Heading off topic, but have you had a close look under the playfield of your Tron to see if it is one or two disks in Tron? You got me curious - I may have been misleading people the last few years on how the mechanism worked. It's a great yet simple feature. However it worked, I hope it makes a return with KISS.
Great choice in games with Tron. I've played it overseas - it's one of my favourites. I'm amazed that there aren't many on location; there are none in Melbourne. That game made a killing on location in the USA - it was the start of the pinball resurgence.
