Update: found another crack in the plastic housing outside of the "pot". Sealed this up with epoxy and everything started working great.

3 days later the leak is back, albeit smaller than the original leak.

Looks like I'm going to have to get a new plastic housing while this one is still working.

Moral of the story: if you have a leak under the pump, always check housing for cracks before doing something drastic like replacing shaft seals and gaskets.