Keep in mind that Nylon does snap easily, so make sure that the slots at the nut and bridge are both free of any unnecessarily sharp edges

There should be an abrupt drop off where the string comes free, and it should be tight to prevent a tone from ringing out against the slot, but it is important that the string is not pulling against a sharp edge or else it will snap under playing tension

High E broke at the ball end within 72 hours of finally staying in tune

I was putting on the top E string and had turned the crank less than a few times, not near enough tension on the string yet to even be in tune yet, and "pop" it broke.

Low E has a bump in it

The second G worked.

High E broke at the ball end within 72 hours of finally staying in tune

I was putting on the top E string and had turned the crank less than a few times, not near enough tension on the string yet to even be in tune yet, and "pop" it broke.

Low E has a bump in it