Patrons cannot enter PIN

People have told me they see this a lot and so do I: patrons cannot enter their PIN when signing on to the computer. When I encounter this problem, I try 1) hit the clear button, 2) check that the keyboard connection is good, 3) try a new USB port for the keyboard, and 4) reboot. May actually need to get a new keyboard. Usually, one of the first 4 options works.