Hi Jacqueline,
Remove the punch card and store it flat. Return the settings to neutral, i.e. the square symbol, so that when you come to use the punch card settings again, the card will not rotate until you set it to. Also move the 'C' levers on the carriage forward to 'O' as this disengages the carriage from the selector bar at the back of the machine.
If you do this every time you finish using a punch card, the machine is ready for plain knitting.
Regards,
Sue, March 2014