So I experienced jumping extruder motor and clogged nozzle and upon investigation I noticed the teeth mark left by the extruder gear on the filament.
I suspect this was causing the problem so I tried to adjust the tension on the clamp of the extruder to avoid having teeth mark. But teeth marks still remains and did not solved the problem.
Now since I cannot eliminate the teeth mark, I focused on the passage where the filament goes thru. I noticed there are edges that could catch or rub on the teeth mark thus making it hard for the motor to push the filament thru. I have to smooth this edges.
So what I did is to put chamfer on this sharp edges. See photos for details. I also put chamfer on the PTFE tube and the one inside the nozzle. Voila!!! problem solved.
Oh one more thing, as much as possible, keep your PTFE tube straight up (not leaning forward or backward) to lessen the drag/friction of filament on the tube.
Hope this helps everyone having the same problem.
Keep printing everyone... cheers!
Oh just to publish this post I have to put a design file along with this so this is just a dummy file.