An ex-MB technician named Alex from legitstreetcars.com is currently tackling a V12. You may find his work on the ABC system and how to remove and strip down an engine to replace a £1 'o' ring in his content.
Although you can jump to the parts concerning ABC, it is worth watching all of his films that deal with the CLK.
Not everyone is brave enough to deal with issues with earlier ABC systems. My wish is that you uncover the truth.