All 6-7 of my 7200's swelled and most cracked where the wires come out of the case within first few runs but it hasn't been a problem. The 6500's I have still look good. I would send back but the cracks so far are only along the edge and haven't gotten bigger but then again I run 6-7 packs so most only get used 1 time per weekend between quals and mains I rarely have to charge.