Mercedes 280SE cyl GroupII 624 non working

Hi , I m new on this forum , so forgive me if i make some mistakes, I m the owner of a  Mercedes 280SE W116 and a 280CE W114.
The 280 SE starting to have some issues from time to time with groupe II cylinders non working up to now with no way to have them woçrking again. Fortunately I have a spare ECU after swaping ECU the car works normally, therefore i suspect an ECU Failure.
I have some knowledge in electronics therefore i hope with some guidance to be abble to repair that group II Chanel. I have open the ECU, but First i don't know how to separate the two boards and second I have no idea what components i need to check first.
Will somebody help me?

Hi Unknown,

I hope you did not brake any of the noses holding it in place on your ECU. It happens quickly. Upper board is screwed on t lower board. Be aware that this is analogue and not digital electronics. And driver transistors are of Ge type. That is why I have ssen people diagnose them falsely as broken and replace them with non-working SI types. Analogue electronics need verification of their output after replacement of components. We are more into a radio / tube TV type of application. Forget capacitors it is semiconductors faults normally.

At least you cannot destroy too ,uch as a 280 ECU is not of too much value. So go ahead and good luck.