A few more pointers for you
1. The air manifold/linkage problem is common. The solution is that after fitting the manifold and then tightening up up the two screw bolts they must be slackened by 1/2 turn and the cowling pulled back.
2. Whilst in that linkage zone make sure it is well lubricated and durring the winter manually move once or twice as they can become stuck. Also the base of the plastic manifold has a sharpish edge and if not fitted well can rub on the main oil inlet. When the manifold is removed always have a quick inspection of the pipes for wear.
3. RAM/DI oil has now been rebadged as HD50 but is the same oil. It does contain a decarb and so does the Quicksilver Premium Plus which can be considered as an equivalent. Do note that the DI oil is only suitable for down to 0 degrees C and below this as the viscosity increases your alarms may sound . An alternative oil may be required for very cold winter use.
4. If you really want to protect against carbon (which can overheat and cook a piston) then use Evinrude engine tunner every 100 hours. Costs only a few £ and is worth every penny. We insist all of our boats are treated between each 80-100 hours. Tunner available from any agent.
5. The time use of plugs is equally important. Dont wait till they start running rough. Change again at 80 to 100 hours. Engine will run better, last longer and fuel use will be at its best.
Like most modern engines they are superb if looked after and should easily achieve 1500 hours of happy boating.
There is often a moan about plug hours and engine hour life. Equate it to a car. Say a car requires servicing at 12000 miles. Driving at 60mph that is 200 hours. Your Ficht plugs like the car will do 200hours but like a performance car it will hugely benefit from an earlier plug change.
Ditto for engine life - a car having done 1500hours at 60mph will have 90k on the clock and it may go on for another 1500 hours or could reasonably be deemed at the engine of its safe and efficent life !