1999 Mercury Sable transmission oil leak

I had my radiator replaced recently and since then I have had a leak at the site where the transmission oil cooler line goes into the upper part of the radiator. I can manipulate the line and stop the leakage for a while, until it is "jarred" loose again. It seems as if something is not seated correctly or a part is missing. There was a plastic clip or something similar that was cracked and the problem still exists. Is there a piece that was lost when the radiator? Thanks, Teresa