I tried to repair my oil pressure gauge in my C3 Corvette and then I really screwed this up! 

I removed the oil pressure gauge from my 1969 C3 Corvette to free up the mechanism. That part went rather well.
However, when I returned to the car, I inserted the brass elbow into the back of the gauge incorrectly. For several days, I thought I had broken the oil feed line and I then bought parts unnecessarily. I felt like a dope. Oh well, live and learn, eh?
This why it's a good idea to take pictures of things as you are taking them apart!
Here is a link to a video by @Problem Solver Garage on how to remove the gauge:
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