Welcome to the forum.
I am not familier with the Pluriel but had a look at the Citroen procedures (these can be bought on dvd from such as ebay) and it says to remove the damper (they seem to call it a folding roof cassette balancer) the folding roof arches have to be removed and then the damper is just unclipped at both ends - looks to be similar to a normal tailgate damper from a hatchback or estate. So it may just need clipping back in but will need to be compressed for the lower end to clip back. The procedure is below but will not include the pictures unless you have the dvd. If you register on the service.citroen website as another professional, member of this forum, you can see the parts diagrams.
Replacement : Folding roof cassette balancer
C5DH0HP0 Replacement : Folding roof cassette balancer
ESSENTIAL : Observe the safety and cleanliness recommendations (refer to the brochure: "RECOMMENDATIONS - PRECAUTIONS").
1. Tool to be improvised -  and  are to help compressing the balancer so the lower end can be fitted.
[ 1] Tool for compressing the balancer, comprising :
- "a" Nut M10 with captive washer
- "b" Flat plate (25 mm x 5 mm)
- A = 250 mm
- B = 25 mm
- C = Ø 7 mm
- D = 10 mm
- E = 12 mm
Solder the nut " a" on the flat plate "b".
[ 2] Quick link (4 mm Ø). - looks like a small carabinier.
Remove the folding roof arches (see the relevant operation).
Pivot the folding roof cassette to the fully up position.
Unclip balancer at both ends at " c" and "d".
Remove the folding roof cassette balancer ( 1).
Clip the folding roof cassette balancer top end ( 1), as "c". Following is to compress the balancer so the lower end can be clipped in.
CAUTION : Use a length of panel ( 3) placed under the tool , to protect the interior trim.
Fit the quick link [ 2] on the ball-joint (2).
Engage tool [ 1] in the quick link .
Fit the folding roof cassette balancer ball-joint ( 1) on the tool , as "a".
Using tool , Compress the folding roof cassette balancer (1) following "e".
Clip the folding roof cassette balancer ( 1) on the ball-joint (2), as "d".
Remove the tool .
Open and remove the quick link [ 2].