Check that general transmission fix link again for the shift solenoid code. The shift solenoids I believe are on the conductor plate. Try swapping that first. It doesn't take that much time. I actually found a full conductor plate "kit" (has everything, plate, connector, gaskets, filter) on Ebay for less than $100 at a German auto supply place in Phoenix, AZ. that was about 1 or 2 years ago. YourMechanic.com guy was an expert with the 722.6 transmission. Only cost me $300 total or thereabouts to fix. Make sure to use the right trans fluid.... I think it was Shell 134 specifically for MBZ/Crossfire transmissions. I have a YouTube video posted about the Crossfire conductor plate swap fix. Search on "conductor plate" and you will see the YourMechanic guy going over the reasons why the design of the originals suck and the newer replacement conductor plates' contacts are much thicker and make better contact under pressure/strain. Viewing the video, I believe you see not only the contacts on the conductor plate, but also those solenoids. The conductor plate can give you a pain in an otherwise really nice car for its time. If you are going to get into the transmission in the first place, replace it anyway, just to eliminate it. The labor will be more than the plate kit cost.