Thanks for the help KenP. I found a post you did on this back in 03', and will try this evening. Here is the text of that for future reference.

Thanks again, kcscout

(Note: Copy of 9/22/03 post from KenP on w140 thumbwheel removal)
This one I've done... and its a pain... to remove the thumbwheels, you have to remove the liner for the small compartment above the center vent... then remove the center vent assembly... that will expose most of the wood strip with the wheels....
On the far right of the wood strip, facing the glove box door, is a small plastic trim piece... you pop that off exposing a screw. Take the screw out and the wood piece, with the wheels, will come loose starting with the right side.
Don't know if you can access the other end of the cable or not via removal of the radio... I went in from the front.
While you're there, replace the two light bulbs for the wheels... :-)
Hope this helps, KenP