Well I can comment on my own experience now, since I've been able to fix my pinball over the week-end! (faulty ram chip, although i had changed it already at an earlier stage: guess I fried it during my repair at some point).
Therer are two advertised multi-ball modes, but actually three way of triggerring them:
- "Instant 2-Balls" : lock a ball in the White House (ramp shot) then drop the 5 targets beneath it. The locked ball is released and then you get to play with the 2 balls
- "Instant 3-Balls"... with 2 balls only : open the KGB Hideout (Eater compartment in the upper-right lane) by shooting the 3 hit targets beneath the capitol (either light the 9 lamps by hitting each 3 times, or hit the right one at first when the lights are cycling). Locking a ball there will put a new ball in the shooter lane, and once fired the hideout compartment will release the 1st ball. You then here radio chatter "Roger Air Force 1, ramp cleared for jackpot!". This lights the 'Jackpot' shot that you can score by doing a ramp-shot.
- "Instant 3-Balls"... with 3 balls : first, lock a ball in the White House. Then, exactly the same pattern as above. Both the KGB Hideout and the White House will release the locked balls, and as mentioned above "all hell break loose". Jackpot is available as well, until you lose two balls (which is called 'Back to level 1' by the game).
Funny as hell, I've spent way too much time playing it over the week-end