2 Things to Check 1st - slide window up, do you see this? - IF YOU SEE THE ABOVE 1) begin by inserting a flathead screwdriver into balance system 2) Rotate 45 degrees so that the 'horseshoe' is parallel to the floor (be careful, as once you have rotated the balance system it will release the tension and the coil will begin to pull the 'horseshoe' up towards the top of the window) 3) once you have rotated the 'horseshoe' slide the balance system up a few inches 4) then rotate it back 45 degrees so that it is perpendicular to the floor 5) Now, slide the window down so that it is even w/ the balance system 6) Tilt the window in 45 degrees so that it is parallel with the floor - this will allow the sash to re-engage with your balance system 7) Once you think the sash is engaged, tilt the window back up into the frame and slide the sash UP towards the top of the window 8) If you see the image below, then you have fixed the problem! 9) If you see the image below, then repeat steps 5-8 again 10) If problem persists, please feel free to call (719)599-9660 for assistance - IF YOU DONT SEE THE BALANCE SYSTEM LOOSE IN THE SIDE - If you are having issues locking your window and the instructions above do not help, please call (719)599-9660 for assistance.