I unwind one turn on the flipper button levers spring on the Gottlieb Games of that era. Then remove the buttons and clean the brass insert in the cabinet and polish the button shaft using emery cloth until they are shiny. On reassembly, one drop of thin sysynthetic lube on the button shaft. Also make sure when you push the button on the cabinet in, that the lever arm is only hitting the actuating blade on flipper button switch stack and not bottoming out on the backing bar of the switch stack. You may have to adjust the position of the switch stack blades or the entire switch stack. Good Luck and pm me with addtional questions if needed.