not much else would could aerated oil if in fact the oil is actually aerated
most obvious and likely is the pick up gasket,pick up pipe and dodgy pump are the next
easy whilst the sump is off to check all 3
infact and I'm sure you'd agree that you or I cold have had the sump off job checked and fixed and back on in less time than we have spent helping on this topic
and earn't some money for our expertise