Download manual here:
http://mirror2.ipdb.org/files/2803/Bally_1975_Wizard_Manual.pdf
Download schematics here:
http://mirror2.ipdb.org/files/2803/Bally_1975_Wizard_Schematic.jpg
and what "fredsmythson" said...
check Game Over relay and check Ball in Play relay to make sure it goes to game over after the last ball is played.