In an online world, training courses like this are about as relevant these days as VHS players.
All of the generalised info that is covered in these courses is readily available at the ends of your fingertips.
Fine for those who work in the industry as their main source of income and want to write it off as a tax deduction though (or generate a bit of extra income on the side ;)).
For everyone else just use google or ask in this forum. Clay's repair guides as one example covers 99.9% plus any troubleshooting problem you think might be unique has been experienced by other machine owners before you.
I concur, but this course is more aimed at newbies and would be a sound introduction into pinball maintenance and repairs. Having aid that, some sellers might want to send their lackeys and part timers for an introduction to shopping out a pinball. But I digress..
clay's guide is the bible. That info ha been around for years, and Clay was the only person willing to put the time into documenting pinball repairs and restoration. I'm sure many would agree, that if it was not for his guides, there would not be as many techs around as there are now.
forums and youtube cover a lot of info, but nothing beats the hands on approach of a course like this.