That is the whole purpose of non invasive tests. Yes the test equipment costs upfront but if you are in the repair business and not just a DYIer it pays for itself fairly quickly in just the time savings alone, not mentioning the gaskets that get torn during invasive inspections. I even looking buying an inspection camera too but so far I have manage to avoid it as I need one that will fit through the 10mm spark plug holes. Not many of those out there and ones that are is too expensive for small shop.
Now the time save by not disassembling unrepairable equipment is time I can spend on repairable ones.
I have gone from taking all day to troubleshoot and repair a string trimmer 9 yrs ago to under an hour for most repair jobs. And sometime less than 15 min as with the Stihl trimmer I did a few minutes ago. The customer explained to me his problem as we walked to his truck and Knew from the description of the problem with the Stihl hedger that he most likely had a plugged spark arrester. When I pull it, it was fully clogged. Cleaned and reinstall for the customer and he off to use it again.
