Hi,
My F5 have somewhat of a sticky button. It's the top right one, the big start-button with the logo.
I have tried to submerge the watch in warm water for a while and it got a little bit better.
Then I tried to rotate the button clockwise and counter clockwise to loosen it up a bit by gripping it between my thumb and forefinger, but it didn't move much. It's like it's designed to have the arrow pointing up towards the glass if you look from the side. I can turn it a little bit in each direction, maybe 1 mm or so. But then it sort of feels like a solid stop.
All the other button I can twist and turn as I want, but not the big start-button.
How does you button behave? Can you turn/rotate the start-button?
(Is it called Start-button? Anyway, the big button with the logo at the top right.) :)