Don't get paranoid, checking out the bike's previous history could reveal all is in order...or not. Better to ride sensibly for now, it's when they are thrashed, along with a high detergent oil, that sludge breaks away to block oilways. But yes, in any major teardown the crank plugs need to come out and that central oilway cleared thro'
Search Great Mechanical Disasters on the Forum for fine examples of what goes wrong in a big way, plus a few good laughs. If any of you folks have anything of a like nature to add, go ahead, we all need a good cheering up.
Swarfy