Yamaha F30C/B water in engine lube oil

[Vic.S]

Above engine (approx 4 or 5 years old) is getting water into the engine oil.

What are the likely places this could get in. Head gasket presumably must be prime suspect but are there any other likely places.

Exhaust cover gasket?
Gasket between cylinder block and exhaust guide?
gasket between exhaust guide and oil sump?

Cracked cylinder block or head?

Any known problems with this engine?

Thanks.