Stein, I saw your post on mbcoupes.com, but I think it got lost in all the traffic.
If placing the car in 2B mode does not yield any first gear, check the vacuum modulator first. It should be on the driver's side of the transmission, about 5 inches from the front with a rubber cap. The vacuum line to it from the intake manifold may have a leak.
If you can force first gear, but not with the throttle during normal driving, check that the kickdown switch under the gas pedal still works.
Those are the easiest things to check before digging into the electronics further. Hope this helps, Andrew Seidel.
85 500SEC Lorinser
83 300D Turbo