I stumbled across this post doing an internet search. The company that owned Caretree (Shaver Mfg.) is still in business but discontinued the Caretree product line in June of 2011. I was one of the ones that used to work there.
If you need parts there is a guy in Tennessee who still supplies a lot of the common parts. His name is Phil Prichard at Prichard Nursery Equipment and his # is 423-413-7225. He worked for Caretree a number of years ago and knows a lot about the spades. He should be able to help anyone out.