This problem has been discussed previously... I dont know if North have fixed it but the 2013 bar(which I have) are notorious for grip failure. One problem is that the grip joins on the underside of the bar which invariably gets impacted by the top of the rotor head causing the grip to peel off. I re glued the grip before it got to badly damaged and then whipped some 3mm chord around the bar in the impact area. It works a treat. You could do the whole bar using different colored chord for each side or use smaller (or larger) diameter chord. I just used cheapo Bunnings stuff but marine supply shops have heaps of good chord options.
www.netknots.com/rope_knots/common-whipping