I have been fighting with these for quite some time, and they are definitely a PITA. I have learned quite a bit, but still have not had a successful build. They are definitely nr-r-nr, and the transitions are actually RIGHT at the wicks. The nr 'risers' are not only stiffer, but are also shielded with PTFE (teflon) tubing as an insulator. I have several of these heads, and love the way they vase on a VV/VW device, but am trying to build them to a lower resistance, for use on mechs, without needing a Kick (or equivalent device). I have found sources for the PTFE tubing, but have not yet ordered it. My biggest problem is how to join the nr and r wire precisely and in a manner to permit actually wrapping the joints into the ends of the coils.
I concur, regarding these being designed specifically to discourage rebuilding, but that means mine will be finding their way to the back-up 'junk' box...at least until I find a practical means of rebuilding them, or until Innokin releases and widely distributes a lower resistance version, which performs better on mechs. (1.8 Ohms in these is still a bit too high for a 'straight' mech.)
Hence, Inn oven's ploy to drive revenue through the sale of replacement heads, has completely backfired, in the case of this previously impressed and outspoken customer.
For the record, I have numerous successful rebuilds of Vision's dual coil Vivian Nova tanks...so the problem REALLY Is the deliberate design of these.