The rear window has leaked behind the back seat . . . . . .
Rear window appeared good but it was leaking behind the back seat. Although the seat was OK the trim wasn't!
and the slimy black wet area under the seat cannot be good for steel! - though it was only surface rust once it dried out.
I made up a new frame using 6mm ply instead of the very thin 4mm ply of the original - and fitted it.
the rear window was refitted just before it started to rain - it kept the rain out but the exposed sealant failed to dry. Later redone with black Seelastic.