Hello,
This issue is very well known at Seat.
Dieselmartin and I were discussing this.
The sealing cord is available for purchase. Martin successfully used this method.
I used automotive silicone and it's been working very well so far, but I know that if I ever need to work on the doors again, it won't be as easy to remove.
Why don't you read a book?
/viewtopic.php?t=13344&highlight=seat+leon+turbo
When using silicone, be generous with it and only roughly wipe away any excess. This is the only way to ensure that everything is properly sealed.
Best regards, Jochen.
p.s. A search would also have been helpful in this case

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