As far as I know there is no serviceable seal. I am not sure what its called, crush seal maybe, but the pressure line into pump is never tight, it should have play. This is by design even though it seems odd.
Quick story: When I put my new line in I read a big warning to tighten to a specified amount and NOT to tighten too hard or the seal will be damaged and leakage will occur. My high pressure line is loose and moves a bit yet there is no leakage. The old line was also loose and I thought it was leaking because it was loose. It was actually the oil filter adapter gasket that was leaking.
But I do not know if this built-in seal is serviceable/replacable or even one time use. REplacement of the high pressure line may be a good idea. Not very expensive either. Autozone had one for under $30 I think.
