I have posted many topics regarding a noise issue with my car, and might have eventually found it after many garage trips and self diagnosis. (MK6 Ford Fiesta Flame 1.4 16V)
When stationary with the engine switched off, with the steering lock disengaged, with the key left in the ignition. I turn the steering wheel left to right and wiggle it to find an annoying knocking noise, and this before I get to full lock.
Now if I am right is this an issue with the steering rack, and tie rod ends that are covered with the steering boots???
This is an idea of the sound I have found via YouTube: