The replacement burner and its companion PCB arrived today. I replaced the PCB in my 513 with this new PCB (If you'll recall I had mistakenly loaded 715 firmware into my 513, "irrevocably".) The FW does indeed reside on this PCB (it was 72A on this replacement board).
Having done a skip '987' (which allows the drive and the PCB to make nice with each other), I updated the FW on the 513 to 727V. Success, the 513 is now a quasi 515.
Then I took the accompanying burner and used it to replace the moribund burner in my V2160A. Skip '987' and I'm back in business.
Thanks to Ron who suggested that the FW is on the companion PCB and Wajo for his incredibly informative site.
Oh, is skip '987' the only skip command that optimizes the board with the drive?