I upgraded the firmware to v2 from the Velleman download page (Firmware_k8200_marlinV2).
Everything is working, except that no or hardly any filament is extruded.
The extruder seems to be working fine, retracts etc without problems. By manually turning the large gear the filement is extruded as usual.
Also when pressing the button in Reptier host the extruder does what it should.
Can anyone give me a hint on where to look?