If you notice any issues with suction on your pump, be sure to follow our suction checklist:
Is the valve is seated well?
The valve should be pushed in all the way and not have a large gap on the valve flaps. Push the flange against a flat surface so the flange lip is sealed, and you should see the valve collapsing a lot if the valve is placed correctly.
Is there too much water or air in the system?
The reservoir and tubing should be full of water with no air bubbles. If there is too much water in the reservoir, the bellows will bulge and not perform efficiently and your nipple won’t be able to enter the tunnel of the pump. You can check this by sticking your index fingering between the bellows on the BSA. If it won't fit or there is too much friction, you can try releasing a little water and see if that provides you with a better fit while pumping.