XDJ-XZ jog wheel scratch

Dear all,

Saturday i had my birthday and ofcorse my DJ set was there aswell. A friend of my was playing, and i did aswell. Also some random guys where playing when i was not there so i was pissed of. 

The next day i cleaned my DJ set and i saw that the right jog wheel was full of scratches. I am fucking pissed of and i am really asking myself the question what could it be?

Does anybody has an idea? The scratches are in a circle around the jog wheel screen. I thought it is maybe a ring?

I really want to know what it could be to prevent this in the future. 

I hope someone can help me.

Best regards,

Joost