One more thing about the 722.6, the 722.6 is known to blow the main transmission computer seals, and the fluid from it will wick-up to the computer-See pictures on post 5 of this thread

My attempt at replacing the transmission plug. - Mercedes-Benz Forum

If you find fluid, replace the connector at the beginning of the thread, but you need open up the transmission computer, and clean it with contact cleaner. Blot it clean and dry. Do it about six to eight times, and then let it dry for six hours or overnight...

Also, you could be on the verge of a new conductor plate. Just for kicks, I would check your coolant for cooler failure too..

MArtin