I realize that what's shown is just a small part of the door handle gasket piece, but has anyone had this cosmetic issue and fixed it? I suppose a black rubber 'string' a few mm thick and glued into the gap would do the trick but where would one obtain this?

 

It would be best to replace the gaskets. They could be allowing water to get inside.

 

Plenty around by the looks.

https://xks.com/i-23896734-door-hand...12035gskt.html

https://www.jaguarforums.com/forum/x...-gasket-38988/

https://www.jaguarforums.com/forum/x...gasket-101640/

https://www.welshent.com/Jaguar-Door...ft-P17373.aspx

 

You could always 'cheat' and use some black gasket goo or mastic. Finely applied and cleaned?

 

LOL - precisely my goal. I have bigger problems with the car than to agonize over this. No one would notice this but me..

 

take it to the dealership to get fixed, should be under $1,000 to get done.

 

^^ I assume that was typed with tongue firmly in cheek....

 

Hopefully!

 

He's probably not too far from reality. My local dealer now wants to charge $168 just for an oil change.