Ouch.

Actually, I agree that working on mobos is a waste of time in most
cases. I've changed clock IC's on some, and repaired some physical
damage, but I wouldn't attempt to make a living doing it. Nobody will
pay a tech five hours to work on a motherboard if they can get a more
modern replacement for the same price.

Now if you are talking about motherboards for PDP-11s, Lisas, arcade
consoles, or something like that, you most certainly can repair them,
make money at it, and use your 20MHz scope to do it.