Merc Actros 3348 gearbox issue clutch servo damaged during repair

Hello everyone,

I would like some help and opinions regarding my Mercedes Actros 3348 (2001, EPS gearbox).
The truck was originally bought in Belgium, and is now operating in Africa.

1️⃣ Original problem:

• Gears 2 / 4 / 6 were working normally
  
  
• Gears R / 1 / 3 / 5 / 7 would not engage
  
  
• No unusual noises — simply impossible to select reverse or any odd gear
  

2️⃣ What happened during the repair:
I was advised to replace the clutch servo/master cylinder, which I bought and sent.
But then the mechanic opened the servo unit, and during disassembly:

• The main diaphragm/membrane was removed
  
  
• The pneumatic piston came out of its housing
  
  
• The internal seals were damaged
  
  
• The piston now “jumps” when pressing the pedal
  
  
• The unit can no longer be reassembled correctly
  

Later, I discovered that the Actros clutch servo is a factory-sealed unit and MUST NOT be opened — it is not repairable.

3️⃣ Current situation:

• The gears seem to engage, but the servo piston jumps violently, which is dangerous
  
  
• The clutch servo is clearly destroyed
  
  
• And the original problem (no R/1/3/5/7) is still not solved
  

4️⃣ My questions:
Can someone confirm that:

• the Actros servo is non-repairable and should never be opened,
  
  
• a jumping piston = servo is finished,
  
  
• and that the real EPS issue is more likely caused by the gear lever, the wiring harness, or the lateral shift actuator, and NOT by the clutch servo?
  

Has anyone experienced the same problem on an Actros MP1?

Any advice, experience, or recommendations (especially from people who know Actros) would be really appreciated.
Thank you in advance!