To get rid of the stale smell, turn machine on and play for a few hours. After the last game, leave machine on for another couple of hours. Slowly walk up to the machine and crouch down near the coin door. Slowly open the door and position your nose near the opening. Take a deep breath through your nose and savour that freshly played pinball smell. This method works all the time and improves with age of machine. After some time, your senses will be so well in tune with pinball that you will detect machines in any room even whilee blindfolded, simply by smell.
