originaly it must have been laminated then the grove cut right through the laminate
When I redid mine I painted the little bit behind the groove cause it wasn't going to be seen and just laminated the little part inftont of the groove
I'm glad I can help and really I don't mind or I wouldn't have offered
good luck, It's looking amazing so far

I've had good luck with krylon Semi-flat (rust proof or something like that) it matches the laminate pretty well and judging by you other projects you know how to do the paint right!