Pump losing it's prime.

The water level in the pump basket drops after the pump turns off and it loses it's prime. I know this is caused by an air leak so I cleaned , inspected and lubed the lid and o-ring and insured it was screwed on plenty tight.

Is there other areas that might allow air to be getting in the system when the pump is not running?

Yes. Every joint and every piece of plumbing may be a source of a leak. There's also a drain plug on the pump. If the pump is the lowest piece in the system, then the leak must be in the pump (my pump sits below my pool and slightly lower than my filter). If, however, the pump is NOT the lowest item then you've probably got leak below it. It could be a cracked pipe or a pin-hole or a badly fitting o-ring in a quick-release or valve joint.