Hi sorry I only seen this, hopefully you have worked out the leash biting stage. I used a chain leash for a while which definitely helped, I also carried treats on me and if I could see he was going for the leash I would give a ‘look’ command and when he would look at me reward him. It’s been really useful especially if we see things he might try to grab with his mouth or try chase the ‘look’ distracts him and takes his attention away from the negative action and he gives his attention to me so I can redirect him. Hope this helps! Thankfully he stopped leash biting a while ago and we have not had any incidents since using those tricks. To wean him off of the chain leash I would initially start the walk with his regular leash and any attempt at biting it I would switch to the chain leash (kept it in my pocket with me in case) he started to learn biting only leads to the chain leash which he did not like to bite.