I am in the process of restoring an old webster chicago fountain pen. I do not know what year it was made in but it is a black chased hard rubber pen with the number 2 on the end of the barrel. To my surprise it had a 14k #3 warranted nib on it. I was able to remove the feed and nib and parts of the dried up sac with some alligator forceps but for the life of me I am unable to remove the grip section to replace the sac. Assuming that the grip section is shellacked in place... what has been the best method for removal of the grip section without damaging the pen?