Figured out what the problem was. With crushing, you need to have the block above the waist, if it's just crushing the legs it does nothing. That's why the pig died, it's all down on that level.
So i moved the piston up one block, and viola - i throw the switch and all i hear are the death throes of the zombies! I went and made one side of the shaft glass so that I could see the victims if i wanted (this time it was 2 zombies and a creeper), and added a steel door and lever at the bottom for loot retrieval once the monster-masher is retracted.
My work is done, I can go to bed now ='.'=
So i moved the piston up one block, and viola - i throw the switch and all i hear are the death throes of the zombies! I went and made one side of the shaft glass so that I could see the victims if i wanted (this time it was 2 zombies and a creeper), and added a steel door and lever at the bottom for loot retrieval once the monster-masher is retracted.
My work is done, I can go to bed now ='.'=