Rest of the description: Then put a bonemeal source into the chest with the "bonemeal" sign on it. Break and replace one of the observers (because they are stuck). Put power sources into the encased chain drives which have the "power source here" sign on them - both should have RPM:64 (with different RPM on the contraption it may not work, if you want to slow down the farm, you can make the RPM on deployer lower). Now you are finished! Bonemal farm design which I recommend: https://www.youtube.com/watch?v=QbLnHtIzXTM.