it's unlikely that it will leak from the lid if it's closed well & snug. the front shaft seal is the one that gets worn, since the shaft is spinning in that seal. the front seal is a cheap/easy fix. you just: remove pump, remove pulley (don't lose the woodruff key), poke old seal with skinny screwdriver or ice pick taking care not to gouge seal mating surface then remove seal, lube new seal and tap into place with a seal driver or close-fitting socket, reassemble.

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1982 300sd from craigslist $800 greased on one tank with NO CONVERSION in the Hot Texas Sun. (currently dead & awaiting engine damage investigation and/or longblock swap)
new daily: '03 vw 5speed jetta tdi wagon. bagged&chipped