Summary

Standard filament placement is too poor. Aluminum 10mm square pipe was used to allow gravity to be used. Nowadays, the filament's pull capacity is weak, so this would improve the print problem.

I use this for the filament cleaners, the PTFE tubes seem to be unnecessary. The printer is modified, so it is very different from the original.

https://www.thingiverse.com/thing:4660210

Maybe you can place about three filaments in parallel, if you are creative.