Ran my OA-55 last summer. Working on a You Tube video. It will have some of what was posted here. The link is to what will be the ending of that video. This is a new camera. I dropped my other one and chipped the lens. They come with a waterproof case so I kept this camera in it to protect it. Well that seems to muffle the sound some. That and the times I have the tiller resting on my camera mount distorts the audio. Later on in the summer I started getting some pre-ignition in the starboard cylinder when starting and trying to run slow. I’ll post some pictures of what I found when I get a chance.
Video link https://youtu.be/-V-pMaYLdTk
A "Boathouse Repair" is one thats done without having tools or the skills to do it properly.