I think the connection between the hot-end heater and the connection within the heat sink is not tight. I am not familiar with this hot-end but most are either the teflon tube is not tight against the nozzle but more likely your heat break is not tightened against your nozzle. I had this issue when I switched to a Slice engineering heat break which tightens against the nozzle. In the long run I purchased a torque tool from them and tightened it up and all was well after that.
But before that I had to get rid of all the oozed filament, even on the threads at the connections. I found an odd trick. NOTE my filament was PLA. I soaked the metal parts in Acetone. It does not dissolve the PLA but rather breaks it down so that anything left over is like dust which can be wipe off easily after it is left to dry.