This issue arises mainly when the wrong placements of spool holder or excessive feed or flow rate settings or dust accumulation on filament spool.
To solve this issue follow few simple steps:
Heat up the nozzle upto 250 degrees (set this in repetier under manual mode)
Then use normal kerosene stove wig (pin with diameter almost 0.3mm) and push the pin inside nozzle hole.
Push and pull the pin inside the nozzle several times.
After this remove the filament from the extruder completely, cut the initial 2inch of filament and insert it back to the extruder and test now
Extruder clogging/ curling issue should be solved now, If not then repeat the process for one more time.
If issue still persists you will have to replace the nozzle.