Received an Esterbrook J pen that needs a new sac. Soaked and ultrasound cleaned the pen to get it apart, remove old ink and sac remnants. After getting out all that came loose, I now look into the barrel and see a half circle "wall" which I initially thought was dried ink. If the fill lever is at the 12 o'clock position as you peer down the barrel, the afore mentioned "wall" occupies the position from 3 o'clock to 9 o'clock and is about 1/8 inch tall, or less, and is at the depth that the end of the section would reach. Is this supposed to be there or does it need to be removed?