Put some shaving cream (the foamy kind) around the outside of the seal on the pot while the pump is running. If the air goes away, then your leak is there. The shaving cream will also eventually begin to suck in where the leak is, which should be evident by a hole showing up in the shave cream (you could probably also see it through that clear lid).

I have used shaving cream several times to find leaks in pipe joints and seals on the suction side. It pinpoints exactly where the leak is.