Geeetech A20M underextruding

[merakogie]

Hello, so I recently bought a used A20M for pretty cheap from someone because he said it was his first 3d printer and couldn't get it to work normally. So when I got it home and turned it on and let it print something it was underextruding. So I tried a few things: Tensioning the feeding on the top but that didn't really help. I replaced the nozzle with a new one (I thought maybe the nozzle was clogged) but still with the same result. Almost no filament comes out. I've pulled the white tubes were the filament is in out of the hotend and it seemed like the filament was pressed inside it. So I suspect that the hotend may be clogged. Is there a way to clean it?