Proper operation depends on your extruder being able to feed the correct amount of material at any given time. Any messing with the feed of filament will likely ruin your print.

Here’s what to look out for. But first, listen closely to the noise your extruder motor is making, it’ll give you a clue.

You can also read our full article on filament not feeding properly.

A stepper motor will start clicking when it is skipping steps. That is in the case of an extruder motor when the force required to push the filament further is higher than the motors strength. Possible reasons include:

Remove the filament from the extruder and check how it looks. Is it deformed, as in no longer round but crushed so that its diameter is now wider than it should be? If so you might want to try to decrease the idler pressure on your feeder gear.

Conversely, if the filament is not crushed, but just has a gouge taken out of it where the hob gear has repeatedly slipped, increasing the idler pressure may restore correct filament feeding. Just don’t overdo it or the problems listed above will likely happen.

This problem is made worse when you’re trying to print something that requires a lot of retractions in a short amount of time. Try to reduce the amount of retractions or set your retracts to be less aggressive.

Check your filament path for excess friction.

A lot of HotEnds, even in direct extruders, include a PTFE liner, i.e. a short piece of Bowden tube somewhere between nozzle and heat break. In most Bowden style extruders, the tube extends all the way from the extruder down into the HotEnd. If this inner tube is worn or degraded (happens when printing too hot, usually above 260°C) the friction increases and might be too much for the extruder stepper motor to overcome.

If the HotEnd uses a PTFE liner and it is frayed or has been cut at an angle. Any gap there will lead to clogs sooner or later as the melted filament will leak out around the outside of the liner causing the liner’s inner diameter to deform and reduce.

When using an Ultimaker: check the PTFE coupler in your HotEnd. It is considered consumable and will need replacement on a regular basis.

Your nozzle or HotEnd is clogged. This could be any of the benign reasons like printing too cold, or too hot, or too fast, using too much retraction or nozzle to close to the bed, etc. But there are also some mechanical things to look into, especially if the problem reappears after you cleaned it.

If your HotEnd wasn’t assembled properly, a common point of failure here is if the nozzle is tightened against the heater block instead of tightening it against the heat break.

Increase the Vref of the extruder stepper, giving it a little more power to maybe push a bit stronger without skipping. But do keep an eye on the motor and driver temperatures if you do.

If you’re using a Bowden extruder, these are also common points of failure:

But still no filament is coming out of the nozzle it is very likely we have a problem right around the feeder part of the extruder.

This could be a sign of a loose motor cable either at the board or the motor end, a broken cable or broken or loose pin in the connector. Or a failed motor. Or wrong cable configuration with leads swapped. If this happens, stop what the printer is doing immediately, let it cool down and power it off!

A broken wire on a stepper can easily destroy a driver chip by creating high voltage spikes as the stepper is connected and disconnected (the same damage can occur if you manually disconnect or reconnect a stepper motor while the printer is powered-up).

Source: https://www.3dsourced.com/rigid-ink/ultimate-3d-printing-troubleshooting-guide