John,
Yea, I think most rst's have this problem (although how many people are aware of this I don't know. Well I have rubbed it down (with a fucking long pole cos it is a bastid to get at!!!) gunna get the hoover in there sum how to suck all the flaky bits of rust out (this what you get when u open the sunroof in the summer, lol) and I am gunna do much the same get some rust treatment in there, and the waxoyl sumhow, what did u use spray stuff? and how did u get it in there? cos it is right at the back and you can hardly get ur hand in there

anyway, was possibly thinking about expanding foam aswell but I don't know what effect that will have, also that is where the sun roof sits at the furthest point when it is fully open, so this will restrict this somewhat I would think.
Let me know. Adam.