416C Cat Backhoe, driver's seat loses pressure over night, is there an easy fix?

Hi, My driver's seat loses pressure over night. I used to have a shop manual for the machine but lost it in our house fire. I'm looking for information on the least expensive fix for this problem. It airs up fine and holds pressure for pretty much a day but bottoms out by the next day. Thanks

416C Cat Backhoe, driver's seat loses pressure over night, is there an easy fix?