i have a quad 400 barnett,last season i had a string break. that string was 3 years old. i took it to my local shop ,they put a new string on it. they also told me that my string had broken where it comes off the cam and that most all failures were due to sharp edges left on the grooves in the cams on barnett xbows . they filed the edges down and fixed the problem. according to most bow companies you should replace a crossbow string and cables every 2-3 years just as regular maintance. my barnett is faster than the tenpoint i just bought and shoots just as good.