Hi and thanks for the question. I've been through this before with a user, but my notes are scanty.
We're going to need to try some stuff. After we find the working solution, I'll explain how I'm deriving this. Hope that's ok.
First thing to try for a NRPN that is a 17A is to convert that to MSB-LSB. 17A is 378, so we throw it into the MIDI byte calculator and we get
http://mididesigner.com/help/midi-byte-calculator/?sum=378&number_of_bytes=2
So the first thing I would try is channel=not-sure, MSB=2, LSB=122. Not sure if this is NRPN 0-127 or NPRN 0-16K. If 2,122 don't work, you might try inverting those (122, 2).
Let me know whether this works and we'll continue from here. Thanks!
Dan