The recommended PLA fixes have not worked in my case. The PLA is leaking from the top, where the all thread meets the heat sink ceramic-like female fitting.Because of the low viscosity of PLA at extrusion temperatures it can flow through the nozzle threads and upwards out of the top of the heater block
I used option 3 (teflon on the nozzle threads) before using the printer. Without delay PLA began pooling on top of the heater block, then oozing onto the nozzle and ruining prints.
I removed the nozzle, saw no evidence of PLA on the nozzle threads, but I have been printing with white and maybe I can't see it. After everything was cleaned, teflon applied in multiple layers to the nozzle threads, I reassembled the hot end and reloaded the filament, this time in neon green.
Sure enough, PLA began pooling on the heater block, no evidence of green on the nozzle threads. After removing the all thread from the heat sink I could see the source of the leak, which has been coming down onto the heater block from the heat sink, not from the nozzle threads upwards.
The female heat sink end is gunked with PLA. I cleaned the all thread and tried using teflon tape to seal this connection but the ceramic- like female end just spins in place and I'm afraid of torquing down on this connection and breaking something.
Any suggestions? In my opinion this PLA design/testing/assembly flaw should be grounds for a hot end recall. This really goes beyond a modification or simple fix.