I believe one way to test for a blown driver is by very carefully and gently pushing the cone and feel/hear for any "scratchiness" or "roughness". If you get any those characteristics you have a bad driver.
I thought you were supposed to pee on it on a full moon. Oh, wait, thats warts...
Fred
------- Blujays1: Spending Fred's money one bottle at a time, no two... Oh crap!