Help, I have a Jack Russell pup name of Biggles, aged 10 weeks. I have never owned a dog before. He bites really hard at times. I have tried ignoring this behaviour - I know puppies are supposed to mouth. "No" works most of the time but not always. I am worried that this will become a problem. Any tips gratefully received. So far puppy training going well and started puppy training classes last week. This really is his only downside - otherwise he's great!