Removing corroded black vibration dampening pads is easy. If you tap the surface of them and they sound hollow, there's corrosion behind them. Also check the outside of the airplane, especially near any penetrations or near lapped sheets for signs of corrosion. What appears to be a small area of corrosion on the outside may be an extensive area on the inside.
I use a plastic scraper to shear under the edge of the pad. The pad will break at the corroded areas. I haven't had much luck removing the non-corroded ones; they're well stuck. If it's stuck on solid, leave it alone; there's no corrosion.
Note that Cessna says that you don't have to replace the pad. See
Cessna Service Newsletter SNL93-3 for lots more info.