Apollo Twin Usb Issue

[Chinguun]

Hello. My name is Chinguun. I want to ask question? I used to apollo twin usb windows version. Before it was everything good. I recently sold to the one guy. He gave it to me back. Because i sold to him my apollo twin usb by very cheap price with all includes plugins and extras. That's why i want to returned from him.Because first i love to use my apollo. It was my best of all time. He bought it from me just one months ago. I am so frustrated for him. I don't know what's happened on my audio interface. Is it broken or i have no idea. Also my English is not good. Sorry for that. I checked my apollo is surface is also buttons and big knob. Surface was few scratches. It's okay i can forget about it. Only big problem is when i put channel 1 small line was on there also when i using my big knob there was 4 5 lines in the middle of volume indicator. I never see before as like that lines and big knob is moving not like tight. He used it very bad only for one months. I will attach photos here. Please help me. Thank you.