If you recently changed a leakly gasket in jandy pool pump it now works great but now have constant little air bubbles coming into pool via the return pipes what is the cause and how to fix problem?

The air bubbles generally mean you still have an air leak either in the lid not being tight or the intake fitting not being tight. Here's how you tell! Be out by your pump when the power to pump is shut off if there is an air leak there there will be drips of water coming out, Just tighten the fitting or the lid just tiny amounts until the leak stops. 90 percent air leaks are from there. Redo the gaskets and pump seal.