Your R checks mean nothing b/c NSS does not just intigrate the starter circuit..it also feeds Ea , ASR , TNNsignal, etc...so , until you isolate every one of those circuits , you can not check the starter circuit.
So , we go in the sequece chain as I posted...

If you are getting power to x27 and no starter, but you get starter with x27 bat jumper. then you do not have sufficient power at x27 from the logic chain [ ign/sw/nss/k38/etc] ...to trigger the starter soinoid...ie, a poor connection in that feed ... Power to X27 has to be the SAME as Bat voltage or someting is bad....that is why we jumper each link in that chain..
to find which one is the culprit....somewhere in that chain is a voltage open or drop....your ohms readings are not needed on this application.I will see if I can post the schematic for starter circuit and then it will be very plain to see this series circuit.
I know it is hard for you to visualize , as it is hard for me to read the schematic and have you come at me with physical wire discriptions and questions.

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A Dalton