Windshield Wipers Not Working

My 2006 S500 windshield wipers have become temperamental. Sometimes they work fine, at other times (usually when its raining and really inconvenient) they don't.
I tried swapping the relays to see if that was the problem (switched position and G and H around) and that did not fix the problem.
I suspect the problem may lie in the switch on the steering column.
I have no way to prove this, so may have to bite the bullet and switch it out.
I only found one video on switching this out on YouTube and its pretty cryptic. The airbag kinda scares me but doesn't look too tough.
Anyone have any suggestions on better instructions to switch this out and if there is anything else to check with regard to the wiper problems?
Thanks,
Boris


