I just had a port replacement last Friday for this exact reason... and I have the Lap Band AP!! From day 1 my doctor could fill but not withdraw fluid. He explained there was a kink at the connection of the port and tubing. Not a fun repair, still really sore almost a week later and it was done in the hospital under consious sedation. On the positive note, I had to have fluid removed before I left the recovery area and the port worked like a champ.