I believe the keyed switch operates a rod that goes down the column a couple inches to the actual ignition switch. May be binding. Remove the column covers and inspect it all.
Not sure if that rod system is on all Fords but several have it.
Panama City, Fl.
I wake up in the morning with nothing to do and by supper time, I have half of it done.
2000 Lightning, s/c, tuned, Basanni, built tranny
Sold them all.....
Previous Mustangs:4 - '66 Coupes(silver/blue/grey/red) '87 GT HO, '00/'02/'07 GT Vert(red)(grey)(black), '68 Coupe, '11 GT/CS, 08 GT Vert