Each drop target in that era actually has two switch events on it.
When the target drops, it has a momentary switch for that individual target, only lasts for a fraction of a second.
When the target is at the bottom, it also closes the 'all down' switch, but this one daisy-chains between all the targets. All the targets in that string need to each be working. In Laser Ball, all the 'L-A-S-E-R' targets are one group, and the 'B-A-L-L' targets are another group.
Knock down all the 'LASER' targets and you should see switch #24 show up, the 'BALL' targets should give you switch #38.
-Hans
