The surround does just pull out if I remember correctly. New ones are available from Island 4x4, I had to do two of mine last year.
They're tough to get back into place looking factory fit as I just couldn't get them totally flat, they're very hard to slide once fitted in place. If I had to do another I'd chalk them a bit in the hope of being able to slide them better into the corners.
The trailing edge goes down into the window runner a little. But they do just pull out. Mine were really crumbly once out, so not a chance of putting them back on