WHL RANGE is not a global, it is stored per patch. I'm guessing 7 is the setting for that patch.
Turns out there is nothing really wrong with the OB-6...some confusion, some user error. Part of the confusion was, indeed, that WHL RANGE is not global, but per patch. It would be nice if you could set it for a whole bank at once, but c'est la vie. Another newbie thing, but I suspect that the ONLY Global settings are the ones accessible from the <Globals> button...duhhh! Everything else must be per patch
The other issue was that I was connected to my Roland SoundCanvas (sc55mkii for those of you who care) which does not seem to play well with the OB-6. I ran out of room to have a separate controller and am using the OB-6 keyboard for myriad tasks. Haven't figured it out completely, but the SoundCanvas seems to send out some kind of message to the controller (yes, I had connected it bidirectional) that resets the WHL RANGE when I use it; also the OB-6 turns the volume/level on the SC as well when patches are changed. The intermittency was from times the SC-55 was turned off. I disabled the return MIDI connection and can now set the WHL RANGE again.