Yeah, I was going to say the only thing you can do easily is flush it through with a degreaser and hope you get it all. But there will be no guarantees you've got it all. It may never be an issue, but the only way to know for sure is unfortunately to remove the baffle plate. That means drilling out the rivet heads and then drilling and tapping to fix it back again.
I reckon a good flush 'n' shake should do it though
