Stuck filament in the extruder of Infitary M508
The hot end can clog in two places.


Heat distortion can cause the filament above the nozzle, at the level of the cooling fins, to melt, expand and prevent further passage.
The nozzle itself may be clogged by impurities.


There are two methods available, depending on the type of clogging.


If the hot end is blocked at the level of the cooling fins, a so-called "Atomic Pull" helps. This is also a convenient method of changing filaments. The hot end is heated to approx. 90°C and the filament is pulled out of the hot end with a bold jerk. The filament does not melt completely and remains tough. Thus the complete plastic is pulled out of the hot end.
If the nozzle is clogged, an "Atomic Pull" only helps to a limited extent.
To clean a nozzle, the hot end should be removed from the holder and the heating block unscrewed. You need a gas burner. With the gas burner the brass nozzle is heated until the plastic is completely carbonized. Wait until it has cooled down and reassemble the hotend.


Post-cleaning advice:
Be sure that the hotend is cooled enough that no heat can creep up the hotend and melt the plastic before it enters the heat block. Without sufficient cooling clogging pre-nozzle is very likely.