3D printer help

[Shahin]

I have a prusa i3 Pro B, Above the metal block there is a gap, my filament gets stuck here and builds up. Any idea why? 

[Hackentosher]

I think that metal block isn't screwed in all the way, causing warm, softened, plastic to bunch up like that. See if you can screw anything in when the hotend is at temperature, making sure to use pliers to touch it.

[makersmuse]

Are you trying to print with flex filaments? The stock mk10 extruders can't handle it - you need to 3D Print a new part that covers that gap to stop it kinking and even then it's a real challenge - print at 10mm/s for any chance. The flexion is an expensive but reliable flexible filament extruder upgrade for these printers if you want to do it a 'lot'.