1. Blockage around feed module
Dual head: Mark each extruder and fan with the number to avoid confusion when you attach the printer head with pedestal.
Unscrew the screws show as the picture and detach the printer head from the pedestal
Check around the feed module and clean the blockage.
2. Blockage inside nozzle
Run the filament load function. It will heat and temperature rise up to certain, it will beep. After the beep you can insert metal rod about 1.75 mm diameter thickest and 60mm length into filament holder on extruder as shown in the picture. Try to do 3 to 4 times pull and push metal rod inside the filament holder of the extruder. On the process the filament inside extruder will exit from the nozzle. And aslo clean around feed module gear.
Insert about 0.36mm diameter thickest metal rod into the nozzle of the extruder and try to do 3 to 4 times push and pull the rod inside the nozzle. Caution nozzle is very hot when load and unload function is running.
This process helps clean the blockage inside the extruder and nozzle.