Thanks everyone for the advice.
Bgpowell, I hooked the good tweeter up to both speakers and it plays fine, so at least I know the internal wiring in the cabinets is still functioning properly. The other tweeter appears to be dead. The voice coils on both tweeters are very dark, not bright copper as they are when new.
As for returning the speakers it's not going to happen with this guy. I was lucky to get $100 out of him based on the condition of the cabinets.