How do I clean the built-in mic array in my JVC Everio GZ-HD30EK?

Like the title says, I need to clean the microphone array that is located on the top of the camcorder. It's an old one that my uncle gave to me, and it seems like there are some tiny spots with dirt, old grime, and... "Crusts?

Yes. Those "crust' also made into the inside of the array, and I need to clean it. The 3rd image couldn't catch that much, but you'd know if you saw it with your own eyes. It also bugs me to have dirt on such an ancient device.

I've tried brushing that with an old toothbrush and some lens cleaner (iso alcohol is not found here, but I will look for it as hard as possible), but no luck.