A couple months ago, a relatively new Prince ExO3 Silver broke (9 o'clock) while I was tying off the mains. I couldn't determine it is any fault of mine. Now everytime I string I can't stop staring at the outside of the frame to see how much it is buldging. I get very anxious when I notice a frame buldging when I'm tensioning the last couple mains. I have a 6 pt Gamma progression electro and I've strung about 300 racquets. I've never been nervous about stringing until now. Some racquets flex more than others and I know it's normal for a racquet to deform some while you string, but is there any rule of thumb to avoid a future break. BTW, my client got a replacement from Prince and I strung it up with no problems, however it was warping like no other racquet I've seen. I really thought it was going to break too.