Once I tell the customer how much the repair is going to cost, it's generally around 1/2 the price of a new machine, so they just replace it.
When I run into something really expensive like a sub-zero, I refer it to a guy who does a lot of them.
25 years ago, I did a ton of sealed system work. Now, hardly ever.
Also, the refrigerant and tools are changing. If you get setup to do R134, etc. now, you're going to own a lot of obsolete equipment when the hydrocarbon machines get more popular. They require completely different tools and techniques.