If your horn stops working it may be a worn out spring loaded contact which is part of the upper bearing assembly on the steering column. To replace it with a new one requires a whole new upper bearing assembly.
An easy fix is to remove the steering wheel and using a suitable soldering iron put a blob of solder on top of the work contact, do not overheat. Additionally a small brass nut can be soldered there if you want a harder surface. The solder blob should last for several years and can be reapplied easily when it wears out.
thanks for this tip, because my horn didnt work. I went out and brought myself a pair of air horns
and the bloody thing still dont work followed the diagram so now i have two horns that dont work.
Any help on this matter would be appreciated.