Must be _another_ trade secret, huh? Don't worry, I won't tell him that
when the leads of an ohmmeter are applied one way across the terminals that
the needle will deflect and slowly fall, then switch the leads and there
should be no needle deflection if the cap is good.

That doesn't seem right. I would say:
1. Disconnect the capacitor.
2. Apply the ohmmeter leads; the needle should deflect and then fall.
If it doesn't fall to infinity, cap is leaking.
3. Remove leads. Wait one minute and apply the leads again.
If needle deflects at all, cap has leaked since being charged up a
minute ago.
4. Reverse the leads and repeat steps 2 and 3. The needle SHOULD
deflect at first, in contradiction to the previous poster's advice.

Yes, cap is cheap. But going shopping for the right value and physical
size takes time - he doesn't have one "in the truck" like you do.
....Dom