If so, read this post from the blog Just West of Crunchy that outlines the problems with Medela.
I used a Medela Pump-in-Style Advanced pump with my first baby. The first one that I bought had motor problems after a month, but Medela sent me a replacement pump within two days. After that it worked great for the remainder of the time that I used it (and I was pumping nine times a day!)
Other problems: the membranes ripped after about a month, so I had to continually replace them. Most disturbing: the tubing started to grow mold in it, and there was no way to wash it out. Medela sent me one free pack of new tubing, but I found out later that they would only do this during the initial 3 month warranty.
It was only later that I read the above mentioned article and realized that the Medela pumps are "open system" pumps. Meaning:
There are “closed system” pumps and “open system” pumps. Medela is the latter. Having an “open system” means that milk can back up through the tubing and contaminate the motor to the pump. And while the tubing can be cleaned or replaced, the motor cannot.
Also meaning that if milk contaminates the motor, it can grow mold, which then could potentially contaminate the milk.
I immediately got rid of my Medela pump and got an Ameda pump (free!) through my insurance. Ameda pumps are "closed system" pumps, meaning that milk can't get into the motor and neither can condensation from the tubing. No mold risks.
I'm now using the Ameda Purely Yours Breast Pump and am very happy with it. No worries about moldy milk to keep me up at night. Thank you to the writers at Just West of Crunchy for alerting me to this issue!