I trolled awhile for a reply, since nobody has jumped on this issue, it appears that my initial suspician was correct: the clip was never properly secured during installation of the outboard. The boat was delivered with a 115 4s and they mounted the 150 4s at the dealership, I suspect all controls were reused during the installation. This is a potentially dangerous issue, so I'm relieved to conclude that it is not an inherent problem with these great Yamaha outboards. Good deal.
