Window seal p38

I was wondering if anyone could advise how to change the front exterior window seal channel. As ours is bubbling underneath the rubber and looks bad. I've got new ones and fitted the back door ones ok by removing the lower waistrail strip and sliding the new one in, but the front waist doesn't look like it comes off as easy with the mirror etc. Thanks

The mirror is easy to take off if that helps.
There is a screw at the opening end of the door.