The lifespan of a string is about 250-300 playing hours (although lower strings may potentially last longer), and we recommend changing your string(s) after that many playing hours. What this means is that if you play four hours a day, seven days a week, you’ll want to change your strings about every 2 1/2 – 3 months. When a string is first put on, it has a crispness, clarity, and power that degrades over time, with a abrupt increase in degradation speed around 250 playing hours. Often, one might feel that their instrument is our of adjustment, when really it is just that the strings are old and need to be replaced.  HOW TO CHANGE A STRING First of all, there are a few things you don’t want to see when you look at the peg box of the instrument. You don’t want to see any loose string ends – they have the potential to vibrate and create a buzz. You also wouldn’t want to see the string touching the side of the peg box – this could damage the string, making it go false, and/or break the string.  Now onto changing a string! Remember, change just one string at a time.  This will keep the bridge and the soundpost from moving and allow time for graphite (pencil lead) to be put in the notches of the nut and the bridge for lubrication. The graphite will assist the string and string winding go smoothly over the nut and bridge. Remove the string you’d like to change. Use a pencil to put graphite into the notches in the nut and bridge where the removed string previously was.  Put the ball end of the string in the tailpiece, ensuring it is hooked at the narrow end of the keyhole. Bring the string over the notch in the bridge, and then slip the end of the string through the hole in its peg, leaving about 5mm (1/4 inch) visible on the other side of the peg hole. Wind the string on the peg, always winding it over the top of the peg. After turning the peg a couple times, catch the end of the string under the part of the string being wrapped around the peg, and secure it as you wind the string so that the string will remain secure.  As you finish winding the string to bring it to correct pitch, make sure it is close to, but doesn’t touch, the side of the peg box.  You’ve changed a string! Now onto the next one…. Check out this video that Bill Lee made with Mimi Zweig. “The Short Story of String Life Span and How to Change a String”