can you dismantle the horn? It may have some crud in it. My GPZ did this and the only cure was to replace the horn. If its mounted somewhere hot ( or mounted to something that gets hot, like the rad) the metal may be expanding fractionally but just enough to stop it vibrating enough to make a noise)
Sorry to hear you're having trouble getting the horn Shell, sure it's only temporary and something to do with his age
JP just said you need to give it a good polish making sure you get into all the hard to reach places and that should cure the problem
Although i can't offer any advice as to the cause other than you may have a faulty relay i can tell you that although it is an MOT failure that is the only time it actually has to work speaking in a legal term. If the horn is not working it is only subject to an advise from any official unless it is likely to become detached ie; hanging by it's wires.
V .. Please tell JP that he cannot run fast enough & there is no place safe enough for him to hide !!
Thanks Dum, It did pass its MOT ... works fine when cold ... just as the bike warms up it stops working & it seems that the more it happens the less it takes for it to stop
Lol WN ... Battery is fine, was brand new at the start of the season as the bike had been sat 10 months doing bog all while I passed lol it's one of the gel batteries,
Will get a new horn see if it's just age to the old one ... Watch this space will keep you updated lol