To remove the pipe,.. take the two water feeding pipes off , one on the top at the cylinder head area and one at the manifold area. Unscrew the large hex bolts at the manifold, slacken the large chrome circle join at the widest part of the pipe (left of the clinder head ), then take off the mounting bolt holding it to the casing (just back from the circle join) Watch out for the large copper seal that is inside the join flange and make sure it don't drop down under the engine. Its an awkward job to refit as you cant get your hand under the exhaust to hold it in place while you try to tighten the large jointing ring,... I used a peice of thin rope underneath to pull it up while aligning it with my other hand ( and a mates too ).
Easy access to the oil pump after that.
The end nipple hasn't just popped out of its seating by any chance has it ?? It just snaps into place and can pop out if it hasn't been 'clicked ' in properly.