Topaz trim pieces

hello,
We have a Topaz that is beginning to show its age! The fixings in the black horizontal trim pieces on both sides are rusty, seized or loose - before I attempt to strip anything I’d like to find out what these are fixed to, is it into the metal bodywork or into wood bonded to the body? I don’t want to wreck anything as some fixings can’t be removed and will have to be drilled out!
Thanks in advance 
[You must be registered and logged in to see this link.]

Hi i'd also be interested to know what they screw into. It seems to hide the join between the original metal roof and the grp hi-top. What l did find was an amazing amount of leaf mould trapped behind ours which also blocked the two drainage holes, one near the windscreen corner and the other about an inch from the rear edge. Its also held in place with mastic along the bottom edge, i suspect removal would be quite awkward.

...if you simply put "gutters" in the search box on the right hand side of the header, there comes up some posts concerning the black mouldings from members with the same problems, and hopefully you'll find something useful.