What to check when I get my old pump out of storage?

[kezoo]

So baby #3 is due in a couple of weeks, and I have a Medela PIS that I bought new for my first about 5 years ago. I pumped 2x/day at work for about a year for each baby (so total time used about 2 years), and it always worked well for me. Now I'm finalizing the last details for the new baby - is there anything I need to check or replace when I get my pump out of storage? I know some mamas have talked about some parts wearing out and thus the pump not working as well. Which parts might those be? I don't want to find out that my pump isn't working well on my first day back to work when I try to pump!!! TIA!