Clogged print core
If there is no material flowing from the print core for at least 10 minutes it could suggest that the print core got clogged due to some dirt or carbonized material. In this case, the print core should be cleaned by performing the hot and cold pull method.
Using the Ultimaker cleaning filament is the most effective way to clean and unclog a print core on the Ultimaker 3 or Ultimaker S5 Pro Bundle. If you don’t have the Ultimaker cleaning filament at your disposal, you can use PLA.
Print core not recognized
If a print core is not recognized by the Ultimaker printer, an error message will inform you about this. The main reason for this is dirty contact points on the PCB on the back side of the print core. When this happens, clean the contact points with a cotton swab and some alcohol.