Just my opinion also, is that meg readings need to be taken with a grain of salt. Charts and graphs will show deterioration of insulation, but they're not an end-all finding. Applying full voltage potential is a lot better than using that 9 volt ohmmeter, but even if you do go twice the applied voltage, there's still nowhere near the stress on that motor and it's components that you get when applying operating voltage to actually make that motor start and run. Some folks use the 1000 ohms/volt rule of thumb for spot checking, and there's nothing wrong with that figure. I just believe there should be a little more thought involved instead of simply using math and charts and calling it good.