Serpentine belt/ fan pulley adjustment

I seem to have some trouble with my serpentine belt lining up with the fan pulley. It seems to ride too far towards the block, the edge of the belt lines up with the very edge of the pulley. I had a problem with a squeak when I recently put a new belt on, ended up replacing the the bearings in the idler pulley, new harmonic balancer pulley, recent water pump and PS pulley also replaced. It still have a tiny squeak when cold, but seemed to go away when the engine warmed up. I was just out driving around and something cut 1/4" into the belt and it was flopping all over the place. I cut off the loose strand and limped it home, but there were only about 2000 miles on the belt. I checked it when idling and the fan didn't have near enough play to reach the belt, so I'm trying to figure out how it got cut. Cut was on the fan side of the belt, away from the engine. Any advice besides pulling off the belt and checking all the pulleys for play?