Well . . . Of course it's never as easy as you think / hope it will be . . . I followed the information in the link ALA_XFIRE provided to the MB forum. I was fooled because after removing the control *****, the bulb remained hidden by a little plastic flap.

At this point I looked in the Crossfire service manual (when all else fails read the instructions). The Crossfire service manual says:

HEATER SWITCH ILLUMINATION
DESCRIPTION
The Heater Switch (3) is illuminated with LEDs whenever
the headlamps or marker lamps are on. The lamp
brightness is adjustable with the dimmer switch
located in the Instrument Cluster. The heater switch
LEDs cannot be adjusted or repaired. If faulty or damaged,
the entire Heater Switch Assembly must be
replaced as a unit. For complete Heater Switch
removal procedures, refer to the Heater Control
removal in the Heating and Air Conditioning section.
(Refer to 24 - HEATING & AIR CONDITIONING/CONTROLS/
HEATER CONTROL - REMOVAL).

HOWEVER, I find that information is not totally accurate. I removed the A/C Heater control unit and eventually did find the light bulbs that illuminate panels around the circumference of the two control *****. Turns out I did not really have to remove the whole unit. The bulbs ARE behind the control **** but are hidden by a little plastic flap. Of course the 10 year old plastic has become brittle and the little flap broke off immediately when I attempted to "open" the flap. These bulbs are in fact not LED bulbs but are miniature wedge base incandescent bulbs with a green silicone cap on them. Look like this . . .

with a removable green silicone cap

Now I'm trying to find out exactly what the bulb number is (it's not regular a GE miniature bulb . . . it's smaller) so I can locate them somewhere and buy a few replacements. I'll try to take some photos of the control panel and update this post so others will be able to reference this thread in the future.