No extrusion  

RE: No extrusion

The last time with no extrusion, it's due to the loosening of the gear of the motor shaft of the extruder

RE: No extrusion

Do you hear clicking sounds once the filament is not coming out anymore? If you pause the print once it doesn't extrude anymore and you then extrude with the extruder move menu option, does it still do so without issues?

In most cases nozzle clogging will be to blame. Maybe in combination with not enough tension on the tensioner gear of the extruder (ie not enough grip for the gears on the filament). If your nozzle for some reason partially clogged previously for whatever reason, your nozzle will become more prone to clogging too. 

The standard remidy to fully free your nozzle is  doing a cold pull. Doesn't hurt to try. 
Here is a guide for that: https://help.prusa3d.com/article/cold-pull-mk3s-mk2-5s_2075

If your issues persist, you can also try to raise hotend temperature by 5-10°C. 

RE:

PS: With an Obxidian Nozzel, you have a hardened steele nozzle. Heat transfer is worse with that one than with a regular brass nozzle. That means you might need those +5 to +10°C nozzle temperature for getting similar results with the Obxidian Nozzle as with a brass nozzle. If you use the default filament settings for that nozzle, which are designed for using stock brass nozzles, you might get into a temperature region where filaments start to clog, or there is simply to much resistence that the extruder starts to slip or skip steps.

Some filaments can handle low temperatures better than others, also within their official temp range.