Thank you! Taking out the air bag was easy, with battery disconnected as you say, two T30 screws easily accessed from both sides released the unit. Found the ground wire from the horn and able to test the switch - which worked fine - perfect connectivity, when the front plate pressed. This meant checking the next link - which turned out to be the clock spring unit - which required taking off the steering wheel. Easy with 19mm socket. Not forgetting to mark the position before removal. 4 screws secure the clock spring unit - and was able to access the horn ground wire behind it. perfect connectivity - whatever the position of the spring - so further I need to dig. The ground cable comes out of the turn Indicator and wiper/lights stalk switch (17A762 ) and disappears behind a circuit board. I can see a relay - Taiko CRX250 - which will probably be the wiper relay? Now - I am not too comfortable taking the circuit board out, as the stalk mechanism are complex and once dismantled, I may not be able to put it back together. I am sure there will be a faulty relay behind it - but I can not see it. I’ve tested it with battery connected - shorting the ground wire and the horn intermittently sounds - then stops, with ticking noise consistent with faulty relay. I am thinking three possible next step: 1. go ahead and take this apart and see if I can find and resolder new relay. 2. Find a second hand stalk unit and try my luck. 3. create an alternative circuit using this ground wire and fresh generic relay mounted elsewhere. I am thinking may be 3. . . . Any thoughts on this will be welcomed - never imagined a simple horn woe could take me this deep. . .