I have an old vickers power steering pump on my 1984 380sl and I have two questions. When you reseal the pump and reinstall it do you have to prime the pump and if so how do you do it? Also there is a plug to the right side of the pully (see thumbnail) It is about an 1 to 1 1/4 across, what is under the plug? Could it be a pressure regulator. Something is keeping the pump from moving the fluid and I have checked everything else? Anybody have any thoughts?

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