Originally Posted by gsxr

The ALDA is not as mysterious as you might think. If the capsules inside have not cracked, the ALDA can be rebuilt by replacing the shaft seal (which seems to wear out & leak after 15+ years, causing part-throttle power loss.) Photos of the ALDA internals are here:

http://www.meimann.com/images/mercedes/OM603_injection/

Just don't force the setscrew when adjusting... a couple of fingers tension is all that should be required to turn the screw after loosening the locknut. BTW, your door latches either need cleaning & lubricating, and/or adjustment...!