I’m assuming there is some wear on the original grooved lug side of the dog which is why you are flipping it around.
Generally, these gearcases have been very reliable in terms of shifting and sealing. The earlier models may have had some issues partially due to corrosion build up around the shift lever causing it to be stiff, which led to only partial engagement of the clutch dog. Needless to say, this was more of an issue on salt water engines.