Ender 3 S1 Mostly Metal Sprite Extruder Issue

[ArtisticMusician]

I have an Ender 3 S1 with the upgraded mostly metal sprite direct drive extruder. Up until last week it would print TPU like a champ. Then out of nowhere it starts skipping and I pull the filament out and it's all bunched up at the end. At first I thought maybe the tensioning screw was off as I didn't think the extruder was clogged. I spent a good amount of time messing with the tensioning screw until I realized that just wasn't the issue. So I decided to open it up and check for a clog. Upon first inspection everything appeared to be ok. I probably took that thing apart 10-12 times, before I noticed that the filament wasn't going all the way down when I was putting it in. So I opened it up again and couldn't really see anything wrong. That's when I thought to break out the original extruder and have a look inside. That's when I saw what appears to maybe be a silicone linig to the tube that exits the gear box and matches up with the hotend. That is missing on my sprite extruder. So I'm looking for confirmation if that is indeed something that should be there. Does it have a name and can I purchase it to fix my issue. I drew a little diagram of what I'm talking about. Any help is greatly appreciated. ExtruderProblem.jpg

[Bikeracer2020]

You need a short piece of teflon or PTFE tube from the extruder into the hot end to support the filament.

[Roberts_Clif]

My hot end started factory with a nozzle screwed into the Heat block then the throat screws into the other side of heat block this in turn slides into the top heat sink.

This did not work correctly as the PTFE tubing kept burning up to fast,
So I made a few changes.

Started with a nozzle screwed into bottom of the Heat block then the throat /w PTFE liner screws into top of the Heat block .
With an added heat sink Fin the screws onto the Throat then this assemble slides into the Top Heat Sink.

Added Heat sink Fin
RepRap M6 Heatsinks.jpg

Throat with PTFE liner

Throat.jpg

Heat Block
s-l1600-3.jpg
Modified Assemble w/Cooling Fan duct "top Heat Sink above X Axis Carriage.

TL-W3M 2.jpg

Now the Life of the Throat PTFE Tubing is increased greatly even at ABS print Temps.