2001 sc2 ignition lock cylinder

i had a problem with my ignition switch lock cylinder binding since the car was new. i had it replaced 2 times. the new one, although it functions better than the previous ones, still has a slight bind to it. when i say bind, i mean that the key sometimes is hard to turn. anyone else have this problem? if so, what did you do to totally fix the problem? i always lube the cylinder with lock ease....