You probably want to keep it original colored, but one of mine had the same kind of stains on it and I painted it REDFIRE!
https://boomboxery.com/forum/index.php/topic/23585-redfire-jvc-rc-m90/
If you want a paint that is very much like the original, use 1993 Mazda Z4 silent silver - effect.
I painted the cassette door on this M90:
https://boomboxery.com/forum/index.php/topic/23585-redfire-jvc-rc-m90/
If you want a paint that is very much like the original, use 1993 Mazda Z4 silent silver - effect.
I painted the cassette door on this M90: