Several people have asked how you tell if the problem you're having with
Zookeeper is related to the coin processor board.
If your game passes all its self tests but when it gets to where the game
should start, it just resets over and over, that's very likely the coin
processor (it could also be a bad ribbon cable). If the game works but give
free credits at power up, that's the coin processor. If you go to test mode
and the highlighted item changes constantly like you're holding the Slew Up
switch on, that's the coin processor.
Those problems can be fixed by removing the coin processor board and burning a
new 2732 EPROM at location U19 (ZA19) with the image here:
http://www.arcadecollecting.com/info/Zookeeper-no68705.zip
Tim