Use a grease gun with a cartridge of high-quality, water-resistant chassis grease, such as type NLGI No. 2 EP, sold in auto parts stores. Grease all linkage fittings as specified in your owner’s manual. With your fingers, work grease into those linkage joints without fittings. Also smear the propeller shaft with grease.
Drain the oil from the gear case; if a significant amount of water comes out with the oil, this may indicate leaking gear-case seals or gasket or both. Have a marine-engine mechanic pressure test the gear case to confirm the diagnosis; have the seals or gasket replaced as necessary.
Disconnect the fuel line at the carburetor fuel pump. Remove the filter screen and clean it by sloshing it in a pan of automotive solvent. Run the engine to use up fuel in the carburetor.
Drain the fuel tank and lines. Disconnect the fuel line gauge assembly from the top of the tank and lift it out. Pour the gas in the tank through cheesecloth to filler out dirt. Pour some gas back into the tank, slosh it around to collect more dirt, then empty again. Clean the intank filter (if used) in a pan of solvent.
If the fuel line has drain valves, open them. Otherwise blow fuel out of the line with compressed air. Remove the spark plugs, pour in 2 tablespoons of fresh two-stroke engine oil, and crank the engine for a second to distribute the oil. Then reinstall the plugs.