I have a WDB463, 300GEL, right hand drive. Horn / hooter has failed. Fuse is OK. Continuity at steering column is OK. But......embarsssingly.....can't find the actual horn unit. Had the bull bar and front grill off. Nothing there... I've lost all credability with my kids. I just want to test the actual unit. Can anyone help?? Thanks. Alastair.