flex filament get stuck Prusa i3

Hi everyone,

I have a Prusa mendel i3. I have changed to flex filament recently but the filament get stuck before it come out from the nozzle. Any suggestion?
This is how my hotend look like. (internet)

Thank you for your time.

Chinaware with wrong hole sizes and teflon liners....
In your case the liner is not bad at all but the rest might be, including your extruder.
First the basics:
Flex needs very low speeds, if you usually print with around 50.60mm/ you might want to slow down to under 20mm/s.
It also needs a very straight, narrow and clean path from the entry of the extruder all the way to the nozzle.
You don't want to use flex filament with a bowden system.

To get it working you either need a proper hotend or work the issues out of yours.
Starting with sanding the inside and ending with pilishing all to the same, exact diameter.
For the extruder you might need to add a teflon liner so the filament won't be able to jam before entering the cold end.
In most cases it is easiest to have a seperate liner that goes all the way from the extruder bearing to the melting chamber of the hotend.