...Have you never seen one of John's videos before??
Nope.
Whenever I come into problems with boards/monitors I tackle the repairs the old fashioned way, by looking at schematics, following flowcharts (like the one you posted), and start with the basic things to look at like checking voltages, logic probing, etc. Failing that, I then contact my homies here and on KLOV for advice. I really don't need youtube videos to show me how to solder/de-solder a cap onto a PCB, and even this video has a lot of basic stuff that I just gloss over.
In the case of my Donkey Kong Junior problems,
I bought the cabinet in 2009, for a wicked price of $125 USD, (the greatest arcade deal I've had in my entire lifetime) down in Southern California while I was visiting my in-laws.
The cabinet had a Double DK board installed, is in great physical shape, but had this problem with the monitor. At the time I only had a week while I was there to look at the problem, and after doing the basic due-diligence, I decided to just shotgun the caps and hope that it fixed the problem.
Failing that, I haven't had a chance to really dive-in and look at it again since I don't live there and when I am there visiting my time is spent hanging out with the family. I wasn't going to pay the crazy shipping rates to bring it up here, so I decided to let my brother-in-law hang onto it and put it into storage for the eventual day that my wife and I decide to move down there to live.