Golfdude, when I pulled my seal away from its original position, there seemed to be a very light, hit or miss applied material on the back of the seal that I thought looked like a "caulking". It had no sticky or adhesive value to it at all, if it ever did. The rubber seal itself is oversized for the area it needs to fit into, and that alone holds it in place.
The seal has to pulled out if you want to see if there is any surface rust beginning to form behind it, there really is no other way to check it.
When I pulled mine out, I only did a section at a time, about 8 to 10 inch I'd say. After I wiped the moisture dry and sprayed the silicone spray on the entire area, I just pushed the seal back in place, and moved on to the next section.
I only used the silicone as a protectant against future water build up since there was no rust showing anywhere under my seal. If you find the tell-tale signs of surface rust, do not use silicone because it will prevent any type of paint from bonding to the damaged area, that needs to be repaired.
I was a little apprehensive about pulling the seal out of its original position myself, for fear of it not wanting to go back in place, but it went back just by pushing it with my fingers and no tools.
Just remember, what Andrew is doing is a repair, what I did is hopefully a prevention.