I've got the following PLA filament that is not feeding correctly into our Ultimaker 2+
It starts to feed and then all of the sudden, the wire 'eats' (read breaks, but not entirely) the plastic filament as you can see on the picture below:
Any hints are more than welcomed.
The photograph and your description indicate that the drive gear is eating the filament because the filament has stopped moving. The least likely problem would be that something is jammed at the spool or between the spool and the entry to the drive mechanism.
The more likely problem is that your nozzle is clogged. It is simple to determine if that is the case. If you have a direct drive mechanism (not a bowden tube type), remove all the filament and release the wheel or bearing that presses the filament against the hobbed pulley, which is the part connected to the motor or driven gear if you have a geared mechanism.
Heat the nozzle up to correct temperature for PLA and attempt to push filament through the nozzle. If it does not move, your nozzle is clogged and has to be cleared.
A nozzle clog can be caused by a too-low temperature or a too-high temperature resulting in burned material becoming jammed in the nozzle.
If you have a 0.40 nozzle, find that size of nozzle tool or use a 0.40 mm drill bit and carefully push and turn it into the nozzle.
Also consider to use nylon cleaning method. This involves heating the nozzle to the correct temperature for melting nylon filament, forcing it into the hot end, then allowing it to cool. Reheating it while pulling on the filament will remove some of the debris. Eventually, it will pass through the nozzle and will also pull out clean, with no debris on the end of the filament. It is suggested to research "nylon cleaning method" to learn correct temperatures.
I have used the nylon cleaning method and have removed debris from overheated filament in the past. I have been able to shine a bright light from below and see the open nozzle after completing the process.
The above steps are identical for bowden type systems and require to remove the bowden tube to access the hot end more effectively. The tube can be removed from either the hot end or the drive end, but force is more effectively applied if the tube is removed from the hot end.
I had a clogged filament. I heated up to 240 C, and pushed a wire up through the nozzle. It took some effort, and much patience is expected. I left the wire inside, as it helped soften the PLA. Then I pushed the filament by hand from top. After some efforts, the needle moved, indicating the movement of the PLA clog. Once the PLA starts pushing the clogged area, some material comes out the nozzle. Keep pushing and after some hours of effort all is flowing fine! The idea was to transport heat to the clogged PLA by using the needle (from the nozzle end). But it certainly requires patience!
It looks like your nozzle is jammed, since the filament is being chewed. You can fix this by heating the extruder up to around 220 C ( or just about 15 degrees above the recommended printing temp for your filament), then attempting to push some filament through the extruder. If this doesn't work, use a small wire and push it through the nozzle a few times, then run some filament through it.
