my little bro just got a mission for hes for trials bike, all set up and rides nice but the rear brake doesnt hold after adjusting, its a v brake and on closer inspection as you pull the lever it bites fine but as you pull it harder the lever comes back to the bar, it appears the actual brake arms are flexing out between the pad and top where cable goes on lol? will a pair of better arms sort this as ive not seen this before on brakes? cheers