Carb's will most likely still be the issue. Their are passages and circuts that cannot be accesed. Their are instances when not even a sonic cleaner can
I've had LOTS of trouble with water getting in the motor from the exhaust system on my 360s. I've replaced every one of the components
That's one of those infamous Phase Maker ignitions, one of the worst ever made. That it even makes spark at all is a miracle.
Check/reset your point gap as if to close they will not open if the magneto plate has some wear.
Thanks Kim, will follow you're advice