hi i know im new here but i had the same problem with my jack 'baxter'. my vet told me to spread my hand out flat - palm down and when he bit or put his teeth on you to say calmly and in a low voice - "no bite" or "no teeth" while you pushed his nose/muzzle down toward his chest with your hand. the vet said this mimicks his mom putting her mouth on his and pushing his head down when he bites as a baby or does something wrong. it did work although it did take quite a few times of doing this. it was also hard at first to get him to understand i was not still playing with him that i was getting on to him instead. he did get it finally and now all i have to say is no bite or no teeth and he will stop.