I have read many one pass posts where people are never able to get F or J on QF however I called One Pass on December 28th to try and get F and much to my suprise I was able to get F on March 14th (LAX-SYD)and back in economy, however after calling everyday I was able to get J class SYD-JFK. So its luck of the draw.
That only left me one small problem, I was actually trying to get to New Zealand, but this is where my 20K AA miles came in handy, was able to get SYD-AKL-SYD in Y, for on 20K miles !
I found there most of the CO agents on the QF reward desk were very patient when checking all the routings. Be sure to try SYD-SFO (2 class cabin) this is a new route and I think they are also starting SYD-YVR.
and lastly if you are from the east coast make sure to ask the agent to check both SYD-JFK & SYD LAX as there is a different allocation (ie my J class seat from SYD-JFK was not available SYD-LAX even though its the same aircraft)
Good luck