i'm wanting to change the locks on the house so we've got keyed alike locks with thumbturns on the inside.  the front door is only a few months old, but i can't get the cylinder out.  it's a composite door with a yale doormaster locking system and a standard euro cylinder.  I've removed the screw that retains the cylinder, but it doesn't even make it slightly loose.  the back door which has the same setup on, the lock slid straight out no bother.  Any suggestions?

Tried turning the key and wiggling the lock, but it was in there solid.  Eventually sussed it this morning.  There's a weird shroud thing around the cylinder with a clamp bolt through it that pinches it together.  Loosen that and it popped straight out.