Mariner gear box noise
My mariner gearboxes are like that, there is no preload on the bearing when its at rest. I have two spare boxes and they both do it too.
The helical action of the gears when running throws the driveshaft up, when you pull on the driveshaft you are simulating what it's like when running.
In contrast I have a Yamaha 60 gearbox and its as smooth as glass without preload.
There is a place on this planet for all of Gods creatures.........right next to my tatties and gravy.