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It looks like you have the Ultra Flo pump, originally made by American.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.
Got a new o ring for the filter lid but I am not sure if its the right one. I got it on, lubed and installed. Can you tell from the pic if this part is correct? Its a smaller diameter than the old one but I think that may be because the new one was stretched from use. I don't know! Blue o ring is the new one. Thoughts?
The one you got looks like part number Lid O-ring – 350013, which does not look like the right one.
How did you determine the part number to order?
DIMENSIONS 6.4" X 0.275"
Product Description: Pump strainer basket lid o-ring is used on various Pentair pool pumps including the Challenger, WhisperFlo, Pinnacle, and IntelliFlo. This o-ring provides a seal to prevent leaking from the pump lid.