Chi Sparky,
"Customers that are too busy to give you the information or resources you need for diagnostics, but not too busy to tear apart the labor bills for your footwork."
Ain't that the truth!!
I also have known the satisfaction of troubleshooting those machines. Unfortunately I don't get enough of them to keep up with it and get a little intimidated by the time the next one comes in. You're lucky to have that type of work 50-80% of the time.
Even though it might not sound like much, sometimes the part I enjoy the most is flipping the switch.
