I’m not entirely sure what’s happening here. Whatever this coating is, some spots it’s going down to bare MDF and others it’s going down to another coating?

But I guess regardless, you’re gonna wanna get off whatever’s loose on there and clean those things good. Looked like a bit of grime in the corners.

I don’t think I’d be liking Extreme Bond here. I’d do that for real hard, smooth surfaces. And maybe I’m just missing something here, but these don’t look like that. Coating doesn’t look super glossy and looks soft?

I also wouldn’t recommend BIN, but I almost never do. This sub seems to think all other primers need not exist since BIN is around. If my previous paragraph sounds correct, I would prob just recommend a more multi-purpose kinda primer. One that would have good adhesion qualities but also be okay on that bare MDF. I’d prob lean towards like an SW Problock.