If you are the original owner you might try talking to Moen at 1-800-Buy-Moen.
Take a look at this link... http://www.moen.com/consumersupport/...ustomerSupport
Who knows you might be surprised!
You might want to get your water tested and talk to SpeedBump and Gary Slusser in the pumps & Wells forum here...
Get that hard water under control!