Apologises if this is the wrong section, there is a nice looking 20vt for sale that needs it's sunroof fixing/replacing. I'm sure I've read somewhere that these are a problem, rust/availability? Any advice?
In that case you've probably answered the question, if they are available then at worse it's a question of replacing the whole thing, assuming they are the same size. I thought there was a specific problem with sunroofs on coops.
Unlikely you need to replace the whole thing unless the (strengthened) draw cords have gone (unlikely) or a slider part has broken. It's usually a motor failing or these days the glass surround corrodes inside its seal. Having said that, probably no harm in taking the whole unit then you have everything at your disposal. Hopefully a new glass/motor will save you the aggro of stripping the roof down internally.