Was listening again yesterday morning (Sydney time) so early evening NY, it appears that its the approach aircraft that you can't hear anymore. Departures seem to be ok, the tower controller was talking to a KLM,which had just landed, about flying into I think Curacao in a 747 but you could only hear the tower and not the pilot.
It would be great if it can be fixed because JFK tower is in my opinion the number 1 feed on here and makes great listening.