Hi,
It may only be part postponed,but if they were oily structures stuck on contacts and preventing the activation of the button, one could think that a dose of heat could thin the thing. So with the screen and the buttons down, with a hairdryer, I moderately heated the "N" button, for 1 to 2 ', 2 to 3 times, and then I tried again and on the 2nd press on the N button the Dec axis started to move. After several tests the button remained operational.I will therefore follow its functioning on my next outings and I will inform you of the situation.

Dominique