Faders going haywire

Best friend died a few months ago I’ve been running his gig with limited knowledge of the board.  The faders show to be buggin out when nobody is touching the board.  Any help would be appreciated 
file:///var/mobile/Library/SMS/Attachments/d9/09/18DA0363-E6CF-4A4D-97A6-B6699CFDC7B6/IMG_3203.MOV