No prob! We all gotta start somewhere.
Since you're new to this, I'll try to explain this a bit further. I'll just keep the focus on the column we're having trouble with.
At the top of the chart you can see which connector that column is on, and specifically which pin it's located at. In this case, it's connector 2J2 pin 6. So if you look at the driver board (lower left board in backbox) and find connector 2J2 (right side of driver board, top connector), you'll see that connector has a bunch of green wires with different color stripes. On that connector at pin 6 is the green wire w/yellow stripe. That wire runs from that connector at 2J2 at the backbox down to the playfield where it connects to one of those 8 switches. Then *another* green-yellow wire runs from that same switch to another of the 8 switches on the same column... And again and again until the last switch in the column is reached (which will only have *one* green-yellow wire). Note that means you'll have 2 green-yellow wires soldered together at most of the switches. One green-yellow wire coming from a switch on the same column, and another green-yellow wire going to the next switch in the column. That's what's called a daisy chain. Basically if *any* of those green-yellow wires break off any of the switches in that column, some switches (or sometimes *all* switches) will stop working in that column. It's important to note if the diode on any of those switches is broken off at either end or touching anything adjacent (nearby switch/lamp/metal brackets), it may cause the same type of problem.
Do you have a multimeter? It can make testing this stuff easier.
Another thought--you may not see a green-yellow wire at each switch in this case because of the way the drop targets are wired. I'll have to see pics of the switches on your drop target banks... on my Black Knight (same era) there were yellow wires connecting the drop target column switches together, which confused me because i was expecting to see a green wire with a black stripe at each one (different column in my case, but same deal). In my case, the green-black wire went to one of the drop target switches, then a *yellow* wire was run from the same lug the green-black wire was on, over to the drop target switch next to it (which was on the same column), then another yellow wire from that one to the 3rd and final target of the bank (also on the same column). Those yellow wires they used on my game were particularly thin and prone to breaking...so be sure to look out for that too. If you find one broken off, you found your culprit.
Sorry if this is too much information or if there's too much redundancy. I'll be happy to clarify anything you need help with!
Good luck!