I have a music keyboard (Korg PA-3x) and it’s been at the corner of my living room for a year or so without touching it. One day I realised the plastic parts around the screen and the area where the joystick is located is very sticky. The plastic used to be a bit soft and now it’s sticky as if it’s covered with oil residue. At first I thought it’s really oil fron the cooking landed on it but when I try to wipe it, I can collect a layer of oily stuff but underneath is still sticky. Because I’m not using the keyboard I want to sell it but with this issue people are hesitant to buy it or they bid a very low price. I tried to wash it with a mixture of vinegar and baking soda but no luck. The layer seems to be very thick and because if the shape of the plastic it’s hard to wash it.
Does anyone know what happened to the plastic and how to clean it?