Cleaning Black ABS

[monza]

Or you could leave it to turn a nice purple color of back wall.

It's acrylic for sure. If you dont like it, the key to not getting it there is don't let it build up. Clean often with a magnetic cleaner. The more it builds up the harder it is to clean and then you'll risk scratches. If you cant access the back panel with a magnetic cleaner then my advice sucks.