Engine oil pressure?

Well, what sometimes happens is the O ring that goes into the oil pump gets damaged or forgotten, Also, the oil pump is driven by the crankshaft, so you need to make sure the oil pump pickup is not clogged with debris, how was the inside of the engine, clean or sludgy? If the later this can be the problem. Here is the location of the oil pump O ring so you can see what I am talking about. Check out the images (below). Please upload pictures or videos in your response of any problems.