Sliding door seal replacement

I have had the usual issues with side windows but I am having issues with leakage past the seal around the door frame. I have tried adjusting / tightening the bolt at the rear but as the seal occasionally slips off at the top I was wondering about just replacing the old seal altogether.It is thirteen years old after all. Stupidly it seems straightforward but through experience I know that nothing is until one has successfully done something a number of times. Has anyone any experience / suggestions/ advice? Take care everyone.

Have you tried to lubricate the seal? With a silicone basedproduct or alternatively I’ve found applying self adhesive foam to the door to make it press onto the seal a little better can work.

Thanks for that. I have also seen on 'Wheeler Dealers', on TV, how Edd solved a leak by inserting a length of thin plastic piping, similar to that I would use when I made home brew back in the day, in the old seal. However my seal is actually beginning to slip off and hangs down directly above the entrance above the electric step so I susppect any measure would only be temporary. Things to think about.

I think there is a company that specialize in car seals for the classic car sector, bound to be able to help you