That is a very hard way to do it.  And I doubt you can pull off the vinyl with no damage. 

Easier way is to dampen the hardboard and press on flat surface to dry 

One way to dampen is to lay card on lawn. Vinyl up.  Put plywood on top to keep it pressed to grass

Leave for a few hours then put card between two sheets of ply and weight down. Leave a few days 

Of course this ain’t good time of year for some of us to try the lawn method.  But you get the idea of gentle slow dampen and then press dry 

Alistair 

> On Oct 22, 2024, at 09:42, Richard Koerner <rjkinpb@sbcglobal.net> wrote:
> 
>  Actually, YES!  Was described years ago.  The answer is to carefully peel the vinyl from the fiberboard.  Then, saturate the fiberboard with water....let water relieve stress.  Then, place on nice flat concrete surface, with addition of heavy bricks all across.  Let dry for several days.  Use quality spray adhesive, like 3M 777, to reattach vinyl to fiberboard.  This all takes time and effort.  I have never done it.  But it all makes sense to me.  Also, this is WHY there are plastic Vapor Barriers.  They appear flimsy but have a dramatic purpose.  Water is INTENDED to bypass rubber window scrapers but then effortlessly drain out of holes in bottom of door.  With compromised vinyl Vapor Barriers, those fiberboard panels are ready to suck up moisture.
> 
>    On Monday, October 21, 2024 at 06:15:41 PM PDT, Eric Caron <ericcaron96@comcast.net> wrote:  
> 
> Hi folks,
> 
>         The door card on my passenger side of my 84 is in great condition except that it bups out at the top middle and I suspect it is from water damage in the past.  Any tips or tricks on getting the card to return to its flat shape?
> 
> Eric Caron
>