... but possibly the disc lifts up out of the playfield to inside his head which then releases them through his mouth which would require a magnet in the centre of the disc ( like on Twister , X-Men etc. ) ...
There is a hole located back behind the spinning disk, and out of sight (I don't recall where I saw that drawing). The lock seems to work by getting the ball past the spinning disk and into the hole at the back. I would guess that from that rear hole the ball is either returned 'under the playfield' or locked to be eventually shot up into the back of Gene's head. The cape behind Gene's head would conceal the ball being shot out of the hole and into the back of Gene's head, exiting from the month.
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?
Regarding KISS, I just checked the KISS Feature Matrix from Stern does refer to the "spinning disk" - so it must be one disk. I don't know where I got the earlier reference to "spinning disks".
