Not long after buying a second hand 913 f fairway a little while ago it developed a dull rattle that felt more than just a piece of grit, so I decided to see if I could find out what was bouncing about. I took off the weight and through the hole I could see something that was light brown and squidgy. With the aid if a thin screw and pliers I managed to pull out a lump of mastic that is about the size of half a thumb. Would this have been in there since manufacture or has the previous owner injected something for some reason. Just curious but at least there's no rattle now.