I am currently removing both the driver and passenger seat to be recovered. I was reading the TIM&JG in regards to the proper look of the seats once recovered. Could someone explain to me in simple terms how the concave pocket in the center is supposed to look? The book states it's the result of compression and tying down of the center section of the inner spring unit, but I am not sure . Better yet, if someone has a picture that would be better. Also did the 61 have a id or tag on the bottom? Thanks