Filastruder Nozzle Leaking

I've been struggling to get my nozzle to stop leaking plastic at the coupling.  I've tried heating up to tighten at 200 and 220 and gotten it as tight as possible.  It still leaks and barely extrudes out of the nozzle opening.  Given that it is still coming out of the nozzle normally it doesn't seem clogged, but I've no idea how to fix it.  My only thought is thread tape but I don't think it's meant to be used high temp.