Horn Change

[AArcticAA]

My dad owns an e53 x5. his horns went out, both of them. I'm looking for the instructions on how to replace them. I know they're located on the left, front bumper. Can anyone clue me in as to the easiest procedure to replace them? (i wonder what caused them to go out in the first place) At 85 bucks a pop i hate to change out the horns only to have them go out again. When i get them out i'll bench test them. It looks like i'll have to take the front bumper off, which seems like no big deal... i just don't like surprises as far as working on cars is concerned. thank you for your input. this seems like a great website.

ps: i own an e34 535ia... her name is Gretchen... gosh i love that car.