Is this the one you have:
If so I may be able to help and save some hours sw#@ring! I assume it is skimming way too wet? If that is the case do the following:
1. Keep both valves open(on the pump as well as on the outlet) and move the skimmer till the neck of the skimmer is about 4 cm's above water level.
2. Put on the collection cup and see how much skimmage you get and move up or down a little accordingly.
3. If that still doesn't work then you can proceed and use the valves. If the skimmer keep in flooding close the valve on the pump until the level drop appropriately. If it is skimming too dry close the valve on the outlet until the desired level is reached.
Hope you can make sense and that this will help a little as this could take a while to optimize. Sometimes a combination of all above steps is required! Give a shout if still struggling...