I'm pleased w my refrigerator (even though it's not stainless steel & over 10 years old). Last time I moved it out to clean the back, & unscrewed the bottom plate, the carbon-like filter? sort of disintigrated in my hands. Is this a sign I need a new fridge - or a CO2 leak? I may be able to get a new free fridge through DWP, but hate to give up the one I have, as everything works perfectly & lots of space. Any suggestions/input is appreciated. TIA