If a Cobra 800 is going in and out of gear it is adjusted.
If you have the black cable it is the original cobra cable and was recalled for safety because it stretches too much. The replacement is a reddish orange jacket. Make sure you have this jacket.
When the drive starts to clunk excessively, or stops going into gear easily (usually one direction or the other, for me it was reverse....) have your cable adjusted. The way that the book says to do it is at the drive end with the drive off. NOT at the turnbuckle style connecting bracket on the block where the upper meets the lower. It is tempting though.
Remember to have a back up shift assist module. It works by suppressing every other cylinder when you go to shift, effectively dropping the revs without stalling, so that it is easier on the clutch and lower gear set. These modules cost about 100 bucks. They can be swapped out at sea.