Does it look correct in blender? Which blender version do you use? (have you tried the 2.7) For me it looks like some faces are probably inverted -> add a two sided material and see if the missing parts appears 
Does it look correct in blender? Which blender version do you use? (have you tried the 2.7) For me it looks like some faces are probably inverted -> add a two sided material and see if the missing parts appears