If the case is disassemble-able then I'd be tempted to remove the whole shroud, or at the very least those bits that are visible when it's on a shelf/hifi rack, then fill, sand and re-spray the whole thing. If you're looking for a matt black hard wearing spray paint then you could do worse than
this.
Aside from some minatures I discovered at my mum's house in a long abandoned cupboard which I've painted up just to see if I had the skills still, I've tried it out on some metal work I need to do for a fireplace surround and it's been brilliant.