Have a Truth and had the same problem. Got new strings and same thing happened again.
Wasn't a sharp object or anything like that, the problem was that the string was a little too
largesothe cam pinched the string. The channel in the cam for the string was too narrow.
What it was actually doing was pinching the string and spreading apart the serving until it broke.
I finally fixed it by using a different cam module(instead of using the 30 inch module and taking
back a half inch, I used a 29 and added a half inch) and reserving around the camwith some good quality serving
material and putting it on real tight. At least I hope its fixed. I was real disappointed too and still am as the
bow is definitely "tarnished" in my eyes as it took a while to straighten out.