Anyone know just how rare/difficult to find this lens is? I bought one, but the aperture diaphragm does not stop down/up when the aperture ring is adjusted, so it's wide open all the time. I can't decide if it is worth $100 to pay the olympus repair guy to fix it or if I should return the item (I paid $450 US for the lens - a hefty price IMO) Did I pay way too much and adding another $100 is way overboard or should I be happy to have found the lens at all and dish out the extra bill to get it fixed? Any opinions? THank you very much!