I just changed the spark plugs on my 1995 E420 -- it turned out to be easier than I was worried it might be (after reading some horror stories here). The 17mm open-end wrench was a necessary tool and made taking off the spark plug connectors relatively easy.
Unfortunately, when removing the last one, I broke the head off the orange bakelite connector:
(A new one for comparison: )
I was able to remove it from the plug and re-install it and it functions fine but obviously I want to replace it as soon as possible. My question is how do I connect the existing wire to the new connector pictured above? Does it screw on or does the metal part need to be opened? Thanks!