Ignition Switch doesn't engage starter?

[Duane, Andrew]

My mother's 1997 A4 has been having a frustrating problem lately. It's
almost like the ignition switch doesn't rotate far enough to engage the
"START" function sometimes. 9 out of 10 times, it starts just fine. The
10th time, it takes 4 or 5 tries to get the starter to go.

The ignition switch has been replaced twice (as have the battery cables,
battery, and starter motor), but the problem persists. Is there a
possibility that whatever is behind the switch is slightly bent or
something? Or are all of the mechanical parts inside the switch itself?