lower unit still leaking !

[pmr2209]

1996 merc 200 still leaking water into foot. made a homemade pressure tester and it held 15 psi for nearly 2 hours. when i had the powerhead replaced the poppit valve seat was moving back and forth with the valve causing in excess of 40 lbs of water pressure. i got this fixed ( of course the mechanic and the remanurfacturer were pointing fingers at each other and i was caught in the middle) but am still getting water into the lower unit. i'm thinking it's the seal directly below the w/p base assembly because the seal below that for keeping the oil in seems to hold fine with the pressure test. is that seal simple enough to replace, and is this even the source of the leak? ,thanks!

[boats.net]

Its not too bad, you will need to remove the water pump base assembly, should be pretty easy after that.