Well, I just came across this snorkel that gave the the biggest challenge so far. It was badly rusted inside, so I should pat my shoulder for opening up the pen and not damaging the parts. It was after a week of effort, anyway. Then I thought it should be just fine from there, until...I heated up snorkel to remove the tube and sac section to re-sac. In my past experience, the tube and sac section are pretty tightly connected and using moderate force it would give way..but not this stubborn pen. I just pulled the tube out! Now I am scratching my head and don't know how to get the sac section out. Any help?