This subject comes up frequently. When my string broke I tied it back together with a square knot.It took me 30 mins to figure out how it worked and to tie it back together. It broke because I over tightened the string to keep it from vibrating downwards. After re adjusting the tension on all the windows I had no more failures. I don't know if newer MH's had a different design or weaker string or what. But in 9 years of ownership I only had one broken string which I caused. I don't understand the need to restring or buy new shades unless you want the room darker.