You can get spare parts to replace the pieces that are problems without having to by a whole new pump. See http://www.bosombuddies.com/index.php?main_page=index&...
We carry all the parts for Ameda, Hygeia and Medela.
I think the way to prevent the problem is to be sure to wash/rinse the parts and let them air dry completely. Tubing is a problem because it is difficult to dry once condensation gets in there. After each pumping session leave the pump running w/o the parts on as others have mentioned.
My understanding is Medela will replace face plates if you have proof you purchased the pump yourself, since they will not allow their dealers to carry face plates as a replaceable part. You may be able to buy spare parts from them, but I don't know.
I hope this helps.
suep
www.bosombuddies.com