Carburetor issue

I'm not 100% sure because of the picture, but it looks like water damage. The last two pics look like the water damage.

Should there have been any indications while operating the engine before the visual inspection of the carb?  Would any water show up in an oil analysis report.

That is damage/wear from a rough-running engine due to not having the carburetors synchronized, vibrations within the gearbox, or an unbalanced propeller. We recommend installing new carburetors (and synchronizing them), doing a gearbox inspection (replacing worn components), and dynamically balancing the propeller, all at the same time. Unfortunately, those carbs need to be replaced due to the damage in the carb body, as the engine will never run properly once the carburetors are worn to that degree.

In the UK we call that certified technician damage, they have the piece of paper but no idea what they are doing, carbs badly out of sync for that to occur, same as one i went to visit today were mechanical balance alone was 6mm out. 

Rotax-Owner wrote:

That is damage/wear from a rough-running engine due to not having the carburetors synchronized, vibrations within the gearbox, or an unbalanced propeller. We recommend installing new carburetors (and synchronizing them), doing a gearbox inspection (replacing worn components), and dynamically balancing the propeller, all at the same time. Unfortunately, those carbs need to be replaced due to the damage in the carb body, as the engine will never run properly once the carburetors are worn to that degree.

concur