Then again, ...
...you might just use it! I have a Catalina 36 with the same head. It's been there since the boat was built in 1984, and just keeps working. Just flush it thoroughly. I had the same leak. You probably solve it the same way I did, just tighten the packing nut at the base of the shaft. I tightened mine by hand once, a couple of years ago, and it has been dry ever since. The leak is incoming seawater, so no big deal if it weeps a little.I still have the rebuild kit, which came with the boat 6 years ago. I think it was 10 years old when I got it. No need to throw out a functioning head just because its 6 or 7 years old, unless you're in the business of selling heads. We keep ours clean on the outside with conventional cleaners, on the inside by just flushing well, and we always add 4 oz. of Thetford liquid - the thick blue stuff. We never have a head odor problem, either. (I think Thetford owns WC now).Good luck, jv