The Royale - S2-E12
Corrected entry: When Data is trying to talk to the elderly lady playing the slots, she is dropping coins and pulling the arm in much too rapid a fashion to allow the wheels to come to a stop. Also, she's continuing the motions as you hear the machine paying out.
Correction: The Royale is not a real place with real people or real slot machines. It was created by an alien race with one dimensional characters and the old woman is just a cliché background character that doesn't interact with anyone. Her actions are completely constant with a poorly written book being interpreted by aliens (such as "an old woman wasting time playing the slots, pulling the handle over and over until she wins and never stopping after.").
Bishop73