[wingnut60]

Jim,
Based on my wife's experience with these shades--when one goes, several others are near death. Suggest you look over all the strings closely while you have the memory of how they restring, and do any others that are frayed because we have found that doing only one in six months doesn't help us to remember how to do them. We went ahead and did several at the same time and it went a lot easier because we were used to the process.
And what others have said about the tension on the strings--too tight will wear them out fast; just enough tension to hold them up is about right.
Joe