Extruder screw – stuck plastic

Polymer Craft Machine Development
1

Hi guys!
I made extruder by Dave instructions. But now I have problem with this machine. Plastic pieces don’t go to the front of tube. Everytime get stuck at behind.

If I clean tube and screw, it happens again. 🙁
Pieces are PET (shreded by Dave shredder).

See my video with problem

I don’t know where can be problem. Please help.
Thank you very much!

3

Oh really? I thought, it must move forward without heaters… Now I’m smarter.
Thank you and have a nice day!

5

Maybe now, video would be functional.

I try PET and HDPE (without heating elements). But every material get stuck on the start of tube.

PS
Thank you Dave for your impressive ideas. Your machines are great!