If you can see through the channels (they're not blocked), I'd vacuum it. Vacuum it anyhow. If channels are blocked,. maybe that clears them.
Doesn't seem coated other than with ashes.
Looks good to me.
I wouldn't bother with a vinegar rinse.
Yea, I meant to vacuum it today while doing a general clean out, but the vacuum is buried behind 7 x-mas crates in the garage that we put over a door... and i just went back and lit a fire. I'll get to it during the next ash clean out if the consensus follows your statement.