Maidenhead Pub Window Weight Change

4 sliding sash windows at this pub/ restaurant needed new weights fitted. The problem was caused by the glass being changed to thicker and heavier glass a few years before resulting in the old lighter weights not being heavier enough to equal the new weight of the sashes.The new weights needed to be square leaded weights because so that they would be denser and so short enough to fit into the old pockets.We know the properties window is more than 300 years old cos the pockets are positioned in the middle .