PeachParts Mercedes-Benz Forum - Transmission Part Identification

I have an 83-300sd - Ive been trying to fix various leaks - recently I've developed a leak from a part on the right side of the trans(passenger) near and above the front most corner bolt of the trans pan. It has a clip holding something in - the clip is the kind with two holes on the ends at you use a special pair of pliers - sorry Im at loss of words on this description. The piece that is being held by the circluar clip is about as big around as a nickle. I can see it leaking when the engine is running. The car has also developed a loping/bucking thing from 3rd to 4th (I think) in the last few weeks. Im pretty sure its not the fuel filters -they are new. Id take a picture but my daughter has misplaced the camera somewhere in the house. Any thoughts ? Ive looked at the peter schmidt website but it doesnt show that side of the trans....

Thanks