For 11B diagnostics set the middle red button on the coin door to the down position then the press the advance button (the one closest to the door)
Display should read 'music test ' then it changes to 'music off'
Now set the middle red button to the up position and press the advance button again

You should be in test at this point - pressing advance again will take you to the next set of tests (it starts in display test - press advance it goes to sound test - press advance again it goes to lamp test, etc)
If you leave the red button up it cycles the tests automatically - if you put the red button down then you can cycle the tests manually using the advance button to move up one test at a time

To get out of test turn the game off

Attract mode is simply what the game looks like when its turned on but not being played - usually a fancy cycle of lights on the playfield and back box. The display will scroll through high scores/jackpot value/free play/etc