I am used to electrically controlled servos being used in other fashions. You could say the starter solenoid is a servo for example. Basically it is a device that a control signal makes perform a secondary function. In this case the controlled hydralic pressure activates the device and makes it tighten a band around a drum. Like an external brake lining on that band locks the drum up when it is tightened.
Just make absolutley certain you have the area where the fluid is coming out before pulling that transmission. Even if you have to put the back end of the car up on jackstands and run the car in reverse. I do not know for certain how many servos there are in this transmision. Two-three strikes me as about right. You at least are only concerned with leakage from them externally anyways. A shot gasket, O ring or cracked cover type of thing as a previous poster mentioned.
Search the archives on how to change front transmission seals and other related things. Others will post better information as well.
I am far from knowledgeable about automatic transmissions. What you are hunting for is within your abilities to find and repair. You are not going into the transmission. At this point you can easily understand why some people thought it was the reverse band solenoid. Hydralic oil under pressure is only directed to it when reverse is selected.