kerfeldt had trouble coming up with new material : `` I wanted to write something heavier than we 'd ever done , still I had all these great mellow parts and arrangements which I did n't want to go to waste . '' kerfeldt had trouble putting together new material : `` I wanted to write something heavier than we 'd ever done , still I had all these great mellow parts and arrangements which I did n't want to go to waste . ''