For anyone dealing with a stubborn or leaking flush mounted gas cap I thought I would share my experience.
My flush mounted gas cap had been getting increasingly hard to open over the last several months. I took it off and cleaned and lubricated it and it seemed a little better but was still kind of a PITA. Recently after stopping to FILL the tank it leaked out of the cap so I cleaned up the mess and made sure that the cap was tight and after I got back home I took it off and attended to it yet again. I did remember reading about these caps starting to leak and ultimately needing to be replaced, then kind of forgot about it. Yesterday when I topped off my tank it leaked again, bad, so off to the dealer I went and they happened to have one in stock for my application. When I mentioned my surprise that it was on the shelf I was told that this is quite common over time. So $70.00 later I was all set, with a much easier to operate and properly working gas cap.
My bike is a 2018 CVO RG with 55K. Hope this helps.