on a standard straight pull trigger, it pulls the 3-way rod backwards when firing. however, with a blade trigger, it pushes the 3-way rod forward, and as such the 1st and 3rd hose on the 3-way must be reversed to make the gun function.
also be wary of over oiling any part of a cocker as it can lead to numerous problems. a small dab once in a while will be enough. otherwise you can suffer from a malfuntioning regulator, or poorly sealing o-rings.
hope this helps.