Luke,

Funny you should mention that, as I've already removed the top of the wiring box. I did this to make a little more room to allow me to pull the valve cover, which I was able to do (barely). I knew I would have to undo the clips to remove to wiring box if I'm to have a prayer of getting the valve cover back on. But I didn't think that unclipping the electrical connectors inside the wiring box would improve my access to the metal clips. I'll give that a try; I'm definitely up for anything at this point to avoid the indignity of towing the car to a mechanic, head bowed in shame. Thanks so much for the suggestion.

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2003 X5 4.4i
1992 Porsche 968
2007 328i
2014 Subaru Forester XT