Tweeter help!

I have a pair of Heathkit as1348's that typically sound amazing. Tonight as I was listening I heard a distinct crackle in the highs on the right side. I think my tweeters are giving up. In this setup there's three Phillips 0162 T15 tweeters, anyone know of a good replacement? I think these are 15ohm tweeters, if I get 8 ohm tweeters should I put a resistor in line to get to 15 ohm? Any advice is appreciated, I'm a novice but can handle a soldering iron and have refoamed my 15" woofers successfully so I'm not afraid to attempt repairs. TIA