Well Professor Henry has happily adjusted to being an only child, is now a bit plump after three weeks. Is a gourmet, now won't eat his kibble without dad's chicken and rice soup or tinned meat who would have thought for a shelter rescue. His one and only behavior problem is that he bites one place on his tail.
What to do? Would tea tree oil work? We never see him do this BTW. Tea tree oil tastes and smells awful.

Elle and Bella chewed the tail at the base and with a process of elimination we eneded up changing the mixer we gave them with the tinned meat.

Can't pinpoint any type of food, but for the last 2 years we rarely see them chew the base of the tail.

Not great advice but hope it points you in the right direction.