windows lock by rollers, cams, or bolts engaging into keeps. majority of keeps have two slots for the cams! to go in. one for full locking and one for locking but allowing air to enter the room (a slight gap).
sounds like you have one side doing one whilst the opposite doing the other.
the cams alignment can be adjusted with an allen key, some with a small spanner, some with a screwdriver.
also your hinges engage into a keep but this does`nt sound like your problem.
levilewy
March 2010