As the noise happens when stationary, thats a new ball game.....!
Does the steering feel notchy at all?
Next, there's one or two things that are in contact with the steering wheel. 1) The indicator stalk cancelling mechanism
2) The air bag contacting ring (name escapes me at the moment)
and thats about it.
So, down at the bottom of the steering column - is anything touching the column as you turn the wheel?
John