Living in Long Beach, we have some older homes that still have the beautiful original windows and hardware. At some point, the ropes that hold the weights to keep your windows from falling down will break. They make alternatives to retrofit your windows and will last many years, unless you enjoy propping up your widows with a stick or other handy object. They make spring loaded replacements with a retractable steel tape that eliminates the need for both cords and weights. Just pick the one that matches the weight of your sash.
The one pictured comes from www.pullmanmfg.com