The white plastic insert pulls out of the trim channel and then you remove the screws and the trim channel and seal rubber comes off. You buy new seal rubber and replace it.
You can also buy new trim insert and replace that too.
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Salem 29RKSS Pushing a GMC Sierra 2500HD!
Gotta go campin!
Some slide seals have a bulb built into the rubber piece or has a lip formed into one edge, but it doesn't look like yours has either. From the picture yours looks like a flat piece of rubber.
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Salem 29RKSS Pushing a GMC Sierra 2500HD!
Gotta go campin!