So after much frustration, jamming and stress I have a few suggestions. They are PRO/Desperate level so here you go.
- Rebuild the extruder- Dual or Unified head, doesn't matter, just get in there and take the guides out.
1A- On the top feeder/guide, drill the holes and insert a new tube, and trim where it would meet the extruder gears into a v shape so it wont get fed into the tube.
1B take out the bottom guide and do the same.
2 infinitely adjust the feeders till you get a clean feed.
3 Consider using a cleaning filament or run through a lower heat filament that will clear your extruder of any old or harder filament.
My take is that they were going for tolerances that would allow the best compatibility with all filaments, and honestly the TPU and flexible filaments truly require no space to screw up. Love my ZMorph but its so much better when I get done hacking it.