one way to tell if it still has some air, pump the lever untill it comes up hard and zip tie it tight to the grip overnight(system under pressure)if there is a small amount of air in the system this can temporarily fix the issue
then you would know that air is it
if this does nothing then look to excessive disc runout
another way to test is to borrow a bigger master see wot happens
then you would know that air is it
if this does nothing then look to excessive disc runout
another way to test is to borrow a bigger master see wot happens