Auto focusing is difficult and seems stuck. Manual focusing works but you can feel the hardness.
This is usually as the result of impact damage (dropped).
LeZot can return your lens to that smooth, silky feel it had when it was new.
We are able to do all repairs on this and most Canon lenses, give us a call at 1-800-286-9027 or email at firstname.lastname@example.org if you have any questions!