Originally Posted by
clough42
Yes, you need to cut out the support bridging across the bottom of the filament channel. I usually use an X-Acto knife. I just insert the tip into the center hole and sweep around the hole to clean it out. If you have a print cooling fan, enable it when printing bridges, and those strings across the bottom of the channel should tighten up and make a nice, flat platform. If your printer can't do this, you'll probably need to use support. Be careful, though. You don't want to be generating support inside the filament channel.
RobH2 has reported that the inside of the filament channel didn't come out clean for him. I haven't seen his prints, so I don't know exactly what he's seeing. The filament channels are octagonal, to try to improve dimensional stability over round holes, and they print cleanly on my printer. The filament slides through cleanly for me with no cleanup.