<p><em>The pictures explain my problem. I have already tried to reduce the retraction but that showed no effect. Thank you for your help.</em> </p>

<p>The effect is a total stop of the print (no material is extruded).</p>

<ul>
<li>Creality CR 10</li>
<li>Cura 3.4.1</li>
</ul>

<p>I recently added this new feeder aluminium block because the 3D printed stock version was bad quality.</p>

<p><a href="https://i.stack.imgur.com/05Kkq.jpg" rel="nofollow noreferrer" title="Filament not entering Bowden tube"><img src="https://i.stack.imgur.com/05Kkq.jpg" alt="Filament not entering Bowden tube" title="Filament not entering Bowden tube"></a></p>

<p><a href="https://i.stack.imgur.com/qzUD5.jpg" rel="nofollow noreferrer" title="Close up"><img src="https://i.stack.imgur.com/qzUD5.jpg" alt="Close up" title="Close up"></a></p>

This is typically caused by resistance in the tube or hotend but in your case it appears to be mostly caused by a very poorly designed extruder.  The filament needs to be constrained closer to the drive gear.  You may be able to drill out the PTC connector to allow the PTFE tube to reach closer to the gears or print a spacer to fit in between but you need to support the filament in that gap.
You can try raising the hotend temperature as a band-aid until you can fix the problem, do not exceed 240 C if you have a PTFE lined hotend. Long retractions can also pull molten filament into the cold zone where it solidifies and make extrusion harder.
As an example, here is a picture of a Bondtech BMG extruder.  Note how the extruder constrains the filament path all the way from the drive gear to the hotend entrance.  While this example is extreme for normal PLA/PETG/ABS, it is required for flexible filament.  A 4mm gap (or closer) should be fine for PLA/PETG/ABS or other hard filaments.