The manual has nothing to say about this and I have had it happen twice. I get past the extruder and well into the throat of the tube but get stuck a couple of cm above the open bore of the print tube. NO NOZZLE PRESENT
I found that if you heat the extruder for a long time that the heat eventually gets up there and softens things so that they will pass.
I also found that helped with the problem of weak extrusion on the left side of the raft at startup.
As it turns out I was mistaken. On my next big print I had the same left side problem with clicking extruder and poor initial lines. On that same large print which was 120 mm in diameter I had severe lift on the right with your HIPS material. I did not that time apply a slurry of dissolved plastic as as sometimes been advised. I have done a few prints with a primitive curtain around the box but since I always used the slurry I don't know whether it was the curtain or the slurry that caused a good result in those cases. I don't think the lift has anything to do with the left side problem.
BTW I find that with HIPS the support is always terribly sticky and has effectively ruined several prints. I have pretty much decided to never use support with HIPS. I just re-engineer the print to avoid the need for support. With ULTRA-T the support peels off almost completely.
I am a new user and an EE. Is there a technical discussion of the ribbon cable issue available? Also is there a drawing of the hot end in cross section so I could better understand the fiber path without taking mine apart completely?