Removing the o ring block revealed sealant that had gone fairly brittle.  Crappy stuff.  I suspect a little vibration loosened something and thus the leak.

Here are some photos of the cleaned port and re seal with black RTV.

Lewis Bjork

I don't think black is the right stuff to use. Red RTV is usually 500 F.

What does it say on the container?

Also I would etch the aluminum to get a better seal.

BTW I hope you are mixing two cycle oil with the fuel and not injecting
the crap out of the "crankcase". It looks like you are doing that in one of the pictures or is that a sensor?

2 cycle oil in the fuel does a better job as it gets everywhere
inside the engine and not just down stream from the injector hole.
2 cycle oil burns cleanly leaving no residue unlike crankcase oil.

Paul Lamar

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