American Products and PacFab were two separate companies bought out (among many others) by Pentair about 20 years ago.
It looks like you have the Ultra Flo pump, originally made by American.
If you're getting bubbles check that your lid o-ring is in good shape.
If so, cut out the silicone around the inlet to the pump, dry thoroughly and restart the pump. While it's running, apply a liquid 2 part marine epoxy (LOCTITE) to the perimeter of the pipe. It will suck in to any gaps, blocking the breech. Let it run for at least a day so it can harden.