D.D.
Hi A.. I don't know if we have the same pump (mine is Pump In Style), but when that happened to me I had to replace the valves. There were two little white valves that are kind of cone shaped, and then there were two cylindrical clear inserts. I had a lot of success with pumping but I could always tell when the valves needed replacement when the suction or amount of milk just couldn't be pumped. I ordered the parts on line (just do a search for breast pump parts) and I ordered some extra to have on hand.
Oh, and I completely agree with the recommendation to try the organic Mother's Milk tea from Traditional Medicinals. In addition to GNC or other health food stores, you can find it at Whole Foods.
Good luck! And it is great that you are committed to breastfeeding!