Rubber seals on my Avondale

[goose]

Hi.
When I open my roof vent I noticed they had 2 seals on it the width side & they were tatty & needs replacing, Do I have to replace it all around or just the both sides any help is appreciated
Goose
ps we are away at the moment and we are using McDonalds each day

 

[Raywood]

I would replace all the seals, as in replacing the defective ones you will possibly disturb the others, and they will probably need replacing soon anyway, unless they appear to be new ones.