Make sure the back office is running and the application is started. Login as adv and verify you can access the system such as pulling up a bowling record.
Check the wiring to verify nothing has been unplugged or cut.
Test the terminal. Remove the data cable and have someone use a paperclip to short pin 2 and 3 on the top row starting from the left while someone else types on the keyboard. Anything they type should appear on the screen when pin 2 and 3 are connected.
This works on the AMF XL, AMF Advantate and Brunswick Front Desk replacement systems.