About halfway through my pumping it seems to lose suction or something. I guess the suction kind of reverses itself, so instead of sucking milk out when it is in a suction, it is doing it in the resting time between pumps. So it isnt as strong. Does that make sense? I dont know how else to explain it. It works great the first 5 minutes and then does this. Everything is still sealed it seems and I have boiled the parts so I dont know what is going on! It is an Avent double electric-forgot to say!