About 8 months ago I replaced the bridge pins on my Martin guitar. I went with the more expensive rosewood pins. Three times since then, including while on stage tonight at a show one of the pins has popped out (at a show in Connecticut last fall I watched the pin arc across the damn room after it popped out!). I'm having terrible difficulty getting the ball of the string to sit nicely under several of the bridge pins. In ten years previous I have never had this happen. Anybody else have this problem? Anybody have any suggestions as to why it's happening and how to correct? Thanks, Jory Nash