I used my horn last night,(something I rarely do) and it stuck on. I
pressed it again and it went off. on checking it (in the middle of nowhere!)
it appears that if I use the left top, it sticks on, Pressing it with lower left, or
upper or lower right it works normal. Is it just sticking. If so, whatdo my learned
friends suggest, WD40?

I had something like this with the buttons on the steering wheel for the radio sticking. I put it down to that I'd cleaned the interior with a spray cleaner the day before, couple of days later it sorted it's self out.

Thanks Hinchy, cleaned the interior last week, so I'll put it down to that