i've had nothing but troubles with her rulers.
i had the same problem as you and they replace it for free.
then i purchased their HST ruler and the marking and cutting lines weren't centered so i never got 1/4 seams and they never came out the correct size.
i wrote to them and they made me provide photos of how off the ruler was from accurate.
once they saw the proof they sent me a new one.
so the best i can say is their quality control is lacking but their customer service will always send you another ruler for free.