I had extra, or too much, side to side play happen on my Viper once and it was loose bolts on a lock collar behind the secondary. So right behind the secondary the shaft goes through a shield, and right on the other side of the shield is where the lock collar is located. Worth a look.
*edit* It's been quite a while ago so it may not necessarily be a lock collar, but you'll see what I mean when you look behind that shield.