at what level do you start? some people would need to start at the beginning, while some others would start (or think they could start) at a higher level. do you charge per class, per year, or free? when you start to show other people how to fix things they you might end up making things worse for them because they will take something apart under your suggestions (or short something out) and now they are worse off then when they started. i like the idea of this, but the logistics are more difficult.
What age of machine do you start with? em, early solid state, solid state, dmd, modern, etc? while a Wizard of Oz/Walking Dead use the same principles in theory, the have slight differences that could cause some issue. If you start with a DMD class game there are differences between them. A williams game uses 3-4 buttons on the door (along with the flippers) to access and navigate the test menu, while a data east game uses a directional switch to first determine if you enter diagnostics or audits/adjustments. someone watching a video of you working on a Getaway and then trying to replicate it on a Jurassic Park is going to be confused.
below i have list a very basic overview of a tiered class program. as you can see, it would be nice for the novice/beginner, but the guy who has been working on his own machines for a couple of years will think that they can skip right to level 3 or 4. what they have missed is the safety video on how dmd voltages can hurt or even kill you.
level 1 - beginner - opening machine (how to remove glass, how to lift playfield, remove stuck ball)
level 2 - curious beginner - switch adjustment (would require level one abilities), how to put machine in test, how to test switch, how to adjust switch, how to use a multimeter (possibly one of the most important tools)
level 3 - troubleshooting (requires use of a multimeter, therefore level two abilities), how to read the test menus, how to check for continuity/voltages, how to know what parts (voltages) can hurt/kill you, how to replace broken components (coils, switches, etc)
level 4 - cleaning (shop job), requires you to remove components (requires level 3 abilities), what to remove, how to clean it, what to use to clean it (ultra sonic, tumbler, etc)
level 5 - restoration process (requires level 4 abilities) - what can be done, what should be done, what should be left to professionals.
as you can see, the list can get intense with multiple courses under each level. for someone new to the hobby or new to self diagnosis, i would think it is great. when i go out on service to someones house i actually tell them what i am doing, what they should be comfortable doing, and what they should leave to someone with more training.
personally i would like to see a class being taught, but i do not think that it will be done by a manufacturer, more likely to be done by a group of people that are willing to put in the time.
just my humble thoughts.