HELP PLEASE, rubber air bellows

Hi peeps, does ahyone know where I can get a very soft/flexible gp air bellows. I am running the new lth left hand side ts1 manifold with a casa air bellows but the panel keeps coming off ( once down the toad/ once held on by the rear spring clip but off the front). I can only think that the movement of bellows rubbing on panel is lifting it off. Any other suggestions gratefully received!!