Cushcraft does carry the parts and if you have proof of purchase (bought it new) you may be able to go back to the re-seller or manufacturer (if purchased direct) and acquire the parts you need. I just ordered an isolator for the R5 vertical that has been out of production for some time direct from Cushcraft. They were very helpful.
After you get your antenna up and working, you'll probably find you can get lower noise levels and better signal reports on a simple inverted vee even at low heights. Every installation is different and you may have a different experience. Tuesday I helped a friend here in town tune his Hustler BTV8 and it was interesting to note how the height from ground made huge differences in the antennas input impedance. Follow the directions exactly!
Could we with ink the ocean fill and were the skies of parchment made, Were every stalk on earth a quill and every man a scribe by trade. To write the love of God above would drain the oceans dry, nor could the scroll contain the whole though stretched from sky to sky.