How in the world do I remove the retaining ring for the headlamp bulb for a 1990 300E ?? I know its not rocket science, and im not the most mechanically inclined, but I cant figure it out. aiaiaiaiaiaii. any help would be appreciated. One failed so I will replace them both. Somehow i removed a small spring from the housing and get get it back on,oooops. I hope I didnt need that