Having access to the biggest USA workshop live hotline databases, I will publish them here and might help some.

Customer Concern: Car has a vibration at cruising speeds of 25 to 35 miles per hour. Also there is a humming like noise.
Average Reported Mileage: 84437

Tests/Procedures:

1. Verify transmission fluid level.

2. Test transmission fluid for signs of coolant by using a test kit. See attached factory service bulletin P-B-27.55/50g for instructions.

3. With factory Mercedes scan tool (SDS machine) or equivalent, perform software update on transmission control module.

4. Further verification can be done with factory scan tool to turn off the torque converter solenoid for one key cycle.

5. Without factory tool function to test and there is no Glycol contamination, replace transmission fluid at least two times and reset torque converter adaptations. If improvement is noticed, replace fluid one more time before considering internal torque converter hydraulic issue. Tech Tips: Some shifting problems may occur due to a control unit software issue. Control units can only be reprogrammed by a scan tool with access to dealer level software. As an example, the Mercedes factory scan tool (SDS) contains the necessary software updates. After updating the control unit may need additional special coding that once again can only be done by a scan tool with access to dealer level software.
Potential Causes

Fluid Level
Transmission Control Unit Software
Contaminated Transmission Fluid


Confirmed Fix Summary
Confirmed Fix

2 - Replaced Radiator and Replaced Transmission Fluid
1 - Replaced Transmission Fluid
1 - Adjusted Transmission Fluid Level

Confirmed Fix Details
Tech Reported Fix Details Confirmed Fix

September 10, 2019 2003 Mercedes-Benz C240, 2.6L, V6, Des 112.912, USA *
Radiator
Transmission Fluid
- Found coolant in fluid.
93,992 miles Replaced Radiator and Replaced Transmission Fluid

September 9, 2019 2004 Mercedes-Benz CLK500, 5.0L, V8, MFI, USA *
Radiator
Transmission Fluid
- Had to drain and fill three times.
73,321 miles Replaced Radiator and Replaced Transmission Fluid

September 10, 2019 2003 Mercedes-Benz C240, 4Matic 2.6L, V6, Des 112.916, USA *
Transmission Fluid
86,000 miles Replaced Transmission Fluid

April 5, 2018 2004 Mercedes-Benz C240, 2.6L, V6, Des 112.912, Canada *
Transmission Fluid Level
- set trans fluid level
Adjusted Transmission Fluid Level