[Elecraft] VFO B is tracking VFO A

[Steve Mollman]

I have a K3 without the sub-receiver. When on 17 meters only, VFO B tracks VFO A. I want to un-link them.
 I have tried pushing the "SUB" button to un-link them as described on pages 6, 14, 22 and 37 of the manual and page 108 of Fred Cady's book.  When the "SUB"  button is pushed (either momentary or holding) I just get the message  "NO SUB".  Nothing else happens.  Firmware is up to date.
This is driving me batty! Does anybody have any ideas as to how to un-link the VFO's? On the other bands  they are un-linked and work fine.

KD9HL-Steve