@tony I've tried putting the vacuum cleaner on the device to try and fix a possible debris option. That's about the compressed air I have available (apart from maybe a bicycle pump). I'm also not sure how to reach it.
I've tried different angles, but still see the same intermittent behaviour... in any way I press, I hear/feel the button being pressed (the 'click'). So I think it is issue 1, button failure...
I had already opened a ticket for this issue.