I would do like I think Bad is suggesting, especially since it is in new paint. The decks are originally glued to the frame (other than the edges); if you can identify where it is warping and translate that to what/where the frame is underneath, you might be able to "change" the attachment of the skin to the frame without ruining the paint job on top. That is, shim/reduce existing glue thickness as needs dictate.
Hope this helps.
No clue, but I'd think panel adhesive would be a good, modern version of what was used. So, since it is between the bracing, I would think you'd want to separate the bracing on either side from the skin and let it find it's new, natural resting position, then reglue. How to separate the existing panel from the bracing without causing dents, sorry to say I don't have any slick suggestions... Maybe another "Cougarnatic" will have an idea?The warping is between the bracing. I would rather try to support the area rather than taking the lid down to bare metal and starting over. What kind of adhesive was used to glue to adhere the skin to the supports?