Unfortunately, I have no experience with Java and have no idea on how to run a trace in Firebug. When I inspect element and view the scripts, there are no obvious error notifications, but I guess that doesn't mean there aren't any.
I'm at the point now where I'm going to use another plugin, because this just clearly isn't working. Shame really, as I've used this before and I know it's usually great.
If there are any other suggestions for fixes, I would appreciate input - as CF7 is still my preference!