When I pull the sash lock lever to tilt window from frame only one side releases?

Q.   Customer from Indiana writes and sends digital photos - with question?? .. When you pull lever at center of window ( sash Lock / Keeper ) to pull in the sash holders to release the double hung window from the frame, only one side pulls in ( or free ) .. Do you know what is needed to replace?

A.   YOU HAVE TO TAKE THE LOCK LOOSE AND UNDER IT THERE IS A STRING THAT GOES TO EACH SIDE. PROBABLY ONE OF THE STRINGS IS BROKEN.