Rear window frame and back bar plastic inserts

Hi all, im replacing my inner roof lining on my cabrio, my prob is although the metal part of the window frame and the actual roof frame are in really good nick the plastic inserts that are in the window frame and the 1 on the rear of the hood ( where the window straps go through and the inner is stapled and glued on to ) have seen better days, a min of 3 hoods have been stapled on over the years. The plastic in the window frame is full of staple end that i cant get out and at 1 of the corners a section of the plastic has snapped and came out, its the same with the bar the inner goes on except the plastic is broken and missing at the top part where the straps go thro. When the hood sits on you can notice this  
My q's is this,
1- can the plastics be taken out of the window frame and rear bar? How? 
2- can u get replacments?
3- or can u fill it with something ie tiger seal or something else?
4- will the staples and glue hold with the tension if it was filled? 
All help is good help cheers

Hi mate, just doing this myself now.

1- yes the plastic frame can be removed. I snapped mine in four places when removing it but using the right type of adhesive, they can be glued back together in the new frame. I used some professional dunlop adhesive.

2- Not sure, second hand from a breaker.

3- wouldnt try filling the whole thing with tiger seal or the like. Staples wouldnt hold.

4- not for long