Where axactly is the string fraying? Is it a release issue? COuld be alot of things but without more info it would be hard to diagnose. Beside checking to see if there is a spur on the cam, check to see if the cams are leaning. Is the string coming into contact with something....clothing, arm gaurd? Keep it liberally waxed also. I have used some strings for several years with an application of string wax and a piece of leather to work it into the string.....rub the heck out of it helps heat up the wax and it penetrates the string.
WW