No, there is no manual for it as the skimmers are pretty straight forward. The article we provided you is very good at explaining where the water level should be. If your skimmer has lots of head and is pushing the lid off, then it means that your tank is very high in organics and the skimmer is pulling them out at a fast rate. Once the skimmer pulls out the excess organics from the tank (and you don't keep on adding them) the skimmer will go back to normal.
If that does not work, then you would be a good candidate for a neck extension.