They get stuck on zombies 9/10 times. It only seems to half-realize it needs to restart from the top of the alphabetic list =(
Same bad luck here (although the explosion when you overdo it is pretty funny)
But i was more lucky with cave spider spawners instead of normal ones. 3 of 3 worked so far.
Maybe that makes a difference, maybe it was just pure luck
It's on Broonie's to do list but he is still very busy with real life stuff right now, Uni ect. He will get round to it when he can but real life always comes first.
