Replacing seat warmer / heater

Been to hmaservice and looking at the shop manual, but nothing clear about how to remove and replace it.  Afraid to start tearing at the leather seat for fear of ripping or breaking something.  Has anyone gone into the seat to replace the heater?  Looking for pointers.  
I traced the heater wiring to an open circuit in the seat back heater (not the seat bench one).  I may have found a used one at the junk yard.  It looks like the heater is somehow integrated with the cushion.
Thoughts?

my driver side heater went out too. I looked online and found some step by steps with other car seats but never had the time to take apart the whole interior. Just search google for seat heater fix or something like that and see what you find.

your gonna need a hog ring and a cutting pliers to put it back. oh yeah you need a razor blade to remove the heater grid from the cushion.