To prevent damage to the top of the piston,
do not use a hammer.
Give a quick hard push downward on the extension and
listen for a metallic click as wear clearance is taken up.
If significant piston motion is felt or a metallic click is heard,
the pin bores can be worn, and the compressor must be
If no motion or sound is heard, the compressor is in
satisfactory condition and does not need to be replaced.
Remove the extension.