I've found this forum very useful so I thought to contribute with my experience on Pluriel roof fixing. Introduction first, you can skip straight to second paragraph to get to the point. I seriously wanted Pluriel when it was new but never got buying one. Maybe it was back then my lust for high performance that overruled the attarction of highly versatile and complex roof combined with truly attractive price postioning of Pluriel. Over a year ago my kids began complaining that our convertible rear seat space wasn't enough for them anymore. Choises: 1. Give up family open top motoring. 2. Buy one with generous enough rear seat space. Result you know. I became fortunate owner of 2004 Pluriel 1.6 SensoDrive. I chose the best I could find. As an extra bonus all my family members prefer this blue colour over other options. It has some dings and scratches and rolls on incorrect wheels but key factors are good: SensoDrive works as beautifully as one can wish, roof doesn't leak and roof works. However at the time of purchase there was one minor issue with the roof: Front right roof interglide was horizontally split. This resulted that front right corner of the roof didn't tighten correctly when closed. It doesn't leak water but whistle is intolerable at highway speeds when roof is closed.
I found it difficult to find interglide set (8401.HW) so I decided to attempt a repair. This is how I did it:
1. Move roof over the rear window (hatch/cassette).
2. Manouvre rear window to rest on boot. I found this most convenient position to do next steps. 3. Unplug emergency operation access on rear window frame. 4. With large flat head screwdriver (I suppose there is also some special tool for this) operate roof (forward/upward) untill interglide in question becomes free from rail. 5. Detach roof opetating cable (for some extra play). Pry black plastic cassette interglide is attached to outwards so that you can undo two small Torx screws scuring metal plate to interglide. 6. Pull interglide free from second interglide and remove interglide, cassette and associated linkages.
(Insert repair attempt below here if you like.)
7. Put everything back in reverse order. For me doing it first time it was bit tricky as all the linkages have to be in correct position to each others to slide back to the rail. Extra pair of hands might help here.
Interglide repair attempt It seems that link inside cassette had become lose causing incorrect operation and brust of interglide. My weapon of choise to repair this POM plastic part was Plastic Welder two component glue. I slightly sanded the surfaces and cleaned everything with brake cleaner before gluing bits together. I went on to fill unnecessary hollows in interglide to possibly gain some additional adhesion and strength. There was one location through the fracture where I could drill 2 mm hole through the part. I glued 2 mm aluminium stick through the part to that hole to gain some extra strength. Next day I dared to close the roof. Interglide snapped when roof was tightening to it's closed position.

I considered having someone to make a CAD model of the interglide and then 3D printing it. After some discussions with people with better understanding of loads, strengts and 3D printing possibilities it became evident that plastic 3D printed part would be unlikely to withstand the pull this part is exposed to. Maybe CNC machining it from aluminium, POM or nylon? Possible but maybe a bit too much effort and cost for me to have it done.
Authorized Citroën parts stores can't supply these anymore. I found one German internet store that was still selling interglide set for 160 euro plus shipping. I bought it. Next day they emailed me that they can't supply this part and I'm refunded. I found car demolition company in the Netherlands that listed this front right corner ingerglide. I asked for price. 326 euro including shipping. For me that is al lot of money for a small plastic part. On the other hand I couldn't find another one and cost of having someone to create CAD model and CNC machining it would also cost considerable amount. Now I'm waiting my part to arrive.