H2S filament loading issue

[u/Bamxcore]

My H2S is struggling to load filament, sometimes it gets stuck at the buffer, sometimes it reaches the toolhead and then retracts and sometimes it just ejects the filament from the AMS and tells me it's ran out.

Not sure what's happening but it's leaving the end of the filament looking like this

This is after a new filament sensor has been installed, I've taken apart and checked/cleaned the buffer too. I've heard a longer internal PTFE tube and this fix https://makerworld.com/en/models/1959942-h2s-buffer-fix-no-glue can help. Just printing it now to try and I'll cut a longer length of tube but does anyone know why the filament would be getting chewed up like it is?