Extruder not working
1) Checking if the extruder temperature has reached the preset temperature, the lowest working temperature for extruder is 175°set up in the firmware. When heating, if it do not reach the temperature you set up(over 175°)，the extruder will be still at the left hand corner(home position) rather than moving to the center of print bed.
2) if the nozzle has reached the temperature you set up, and x,y,z stepper motors work correctly, but filament does not come out from the extruder . I have some tips for you
If the motor do not rotate, maybe those parts or components have glitch.
①The subdivision of the stepper motor is 1/16. It means you need to plug all jumper caps.
②Please see if the stepper motor or motor cable is broken. You can verify them by plugging them to another working motor connector such as x or y.
③Please see if the stepper driver board of extruder is broken. Simple test: swap the extruder driver with a good driver. Then check if extruder can work well or not.
Besides, the voltage between potentiometer and GND is 0.8V-1.2V. if it less than 0.8V,you should increase it by tightening the potentiometer(screw) Symptoms of not enough current are skipping steps and poor microstepping linearity. Too much current will cause the motor or the driver to overheat. When the driver overheats it shuts down for a few seconds and then restarts again when it cools. This makes the motor twitch when it is stationary and pause during motion.
④In rare case, the motor do not receive signal that causing stepper motor not running
In this case, one of reason is you do not burn correct firmware or the firmware has bug. You can reinstall the firmware in this link.
Another reason is some pins near extruder motor are shorted out.
If the extruder motor can rotate, but hear click noise or the extruder motor move in a narrow range. In this case, please check whether the gap between idler wheel and gear are too large and the pressure is too small to drive the filament. you can refer to this link.
1.You have to make sure the filament has entered the throat rod or it will also make click noise.
The method to verify if the nozzle is clogged.
You can verify if the nozzle is clogged by following ways.
Heating the extruder to 190°-210°(PLA),or 230°-250°(ABS).When finish heating, please press one end of lever with one hand, and extrude filament with force with another hand. If filament could not come out from nozzle, the nozzle is clogged.
Factors causing nozzle clogging.
The temperature you set up for extruder is not high enough.
The gap between nozzle tip and print bed surface is not high enough. The best distance fot the gap is the thickness of an A4 paper. If the nozzle touch the print bed tightly without room. It is easily clogged.
If the nozzle is clogged indeed, please clean it with drill(needle).
1. Stopping the nozzle with repetier host, then move nozzle away from printing object.
2. Heating extruder （PLA190°-210°，ABS 230°-250°）,pull out filament from nozzle to prevent further clog.
3. Remove the cold end, just leave the nozzle.
3. Clean surplus jam with the needle, please be careful and gentle as there is a tube in nozzle. Please do not damage the tube when cleaning jam .
4. Assemble the fan, heatsink and extruder motor, replug the filament to nozzle.
5.Here are some videos showing how to clean the jam, please check this post: