Well, here I am. Went to work for a MB dealer in 1974. Spent three years there and a life time later. I can fix those carbs. Don't expect to find many others able to say that. Don't expect to find many who care.
I don't know where to start about repair. You almost have to be there. MBDoc has the final blow spelled out. Once the top is warped, heroics are necessary. Aside for a bushel of mods and adjustments, timing is ever so important with those motors. Most carb problems can be partially masked by a few degrees of timing.
If you want to fix the carb let me know.
Owner 24 bay BSC
Bosch Master, ASE master L1
26 years MB technician