I'd be delighted if nogin answers you, and he may, but I am not sure he is still active. His last post was May 3, 2010.
No doubt you have already discovered that information on Islanders is hard to find. Islander built great boats but the company appears to have been badly run financially. Already financially weak after a move offshore to cut building costs, it succumbed to the disastrous 10% luxoury tax in the late '80s.
In lieu of nogin's answer, I'll point you to Islander information I have found.
- First up is this Canadian site that features some good general information: Islander Sailboats. Randall Marquis started the site, but I think Bob Everson has taken it over. It isn't very active but is a good source for older info.
- Secondly is the site that, confusingly, is also called Islander Sailboats. It has good general information too, but I thought this one would interest you because it has a good boat owner's list for four different Islander 21 owners with e-mail addresses in mailto: form. Perhaps you could find out more about the boat from them.
- Finally, I thought you might be interested in Sailboat Data's general Islander information and Islander 21 Information.
Hope this helps!