Answer: The tool requires proper lubrication to prevent premature wear - keep it well oiled and it will continue to perform well.
If a tool is used continuously every day, it is a good idea to add 2 drops of oil at the start of each day.
If you experience the pneumatic sander gradually feeling slower, add 1-2 drops of oil into the air inlet and keep the machine running for 30 seconds so that excess oil is drained.
Make sure you are using correct oil for pneumatic tools. Only oil pneumatic tools our electric tools do not require and oil. If a sander is not properly lubricated, it will wear prematurely and perform poorly. However, the sander should not be over-lubricated. If there is oil dripping from the muffler, then the tool is being oiled too much. If the filter is saturated with oil, the muffler must be replaced.
If available, use an FRL unit - FRL stands for Filter, Regulator and Lubricator.