DDJ T1 fixable issues? or is it defective?

hey I just bought a used in a like-new condition T1.

it's working alright, but I'm having issues with it and I hope you could give me a solution to all of them

1. The jog wheels are not very sensitive (not the top scratch surface, but the sides). when trying to beatmatch, im moving the wheels really slow for the beat to match, but traktor just won't react to it, however if I speed up a little abit it would react perfectly.

2. When get a volume fader (A-B-C-D) to the bottom the song would simply stop and go back to its starting point, how do I fix this?

and one more thing, I managed to get the loop button to working as long as I push it, but then I restarted my computer and now when I click on it, it works, but then I need to click again to release it, wheres the setting for it?

thank you