I think you should have calculated how many degrees you needed to move the pump shaft, and in which direction. You also need to figure if you are working in crank degrees or pump degrees. (One crank degree = 1/2 pump degree). Then you would just pull back the pump out of the spline, rotate the pump shaft the correct amount in the correct direction and put it back in.

I don't know how your engine is designed. Perhaps you can align the marks you found on the pump, and then set the crankshaft to the proper corresponding position and reassemble. A manual for this engine should have that info. I think it is unlikely that the marks on the pump will correspond to the same crank angle at which the pump drips, but I do not know.

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1987 W201 190D