Just thinking on this further, at first glance it may seem wrong from a certain perspective to put any kind of extra effort into older machines that are continuing to age and will eventually be replaced anyway. There are larger factors at work though, and very practical reasons to get more into this type of work.
I have studied deeply into economics for many years and it's obvious this country has been in a prolonged economic contraction that has only been kicked into high gear by the COVID fiasco, which has put countless people, companies, and entire industries out of work. It's going to get much worse before it gets better.
At the same time it's also clear that appliances today aren't built as well and often don't function as well as they used to. They are very expensive to purchase and maintain. They don't last, and the repair costs can be astronomical, just from parts cost alone. This is also going to get worse, and won't be getting any better. This is why I have a hard cut-off date of 2007-2008 for appliances (including automobiles and any other 'consumer' appliances) that are to be invested in and used long term in my household. Not coincidentally, that's when this current long term economic malaise began in earnest. I see the hell people are going through out there with late model junk and want no part of it.
The average person is tapped out and living off credit cards and home equity. That's the only way they can afford to keep spending so much. All that's in the process of drying up as we speak. The road ahead will be catastrophic to the 'consumer' economy and lifestyle. Many people simply won't be able to afford the repair bills or purchase price of newer appliances--and the tried and true older models will increasingly be in demand by the wise ones.
Likewise, there's only so much of this "high efficiency" garbage that people will stand, when it starts seriously cutting into their quality of life. There will be a backlash against that.
It's obvious by the high 5-year failure rate alone that old school appliances last much longer than the new junk, and work better also, so that's what I prefer to keep and use for the long term. $500 for a circuit board? Not on your life. Others will increasingly feel the same way, although those most caught up in the "keeping up with the Joneses" mentality will of course be the last to learn.
In a way this whole "appliance repair industry" is new to me, a completely unfamiliar thing, because I didn't grow up in a household that called the repairman when something broke; or ever, at all. I was taught to fix it myself, because a) I can do a better job than the repairman 98% of the time, and b) it costs too much anyhow. I was taught to invest in quality equipment, lots of tools, plenty of spare parts, and always be increasing my skillset so I can do every job, no matter how complex.
I've also been fortunate to spend many years hanging with the O.G. hot rodding crowd in central Tennessee, home of moonshiners and whiskey cars, learning all about building, fabricating, rebuilding engines and transmissions, wiring, electronics, all of it. My favorite automatic transmission is the TH-400; it's child's play to rebuild. A washer transmission? I could do at least a dozen of those a day, and love every minute of it.
Others who disagree with this philosophy will prosper for a time, as long as the credit cards and spare parts hold out, but will have to learn the hard way when things get really tough. In 10-15 years, only the techs who can truly fix things rather than just swap parts will still be around.