have you tried to maybe just put hot water in the center of the disc and not over the GT? not sure if this would be enough water to help but it may be worth a shot.
I have not tried that. I imagine that if it were a case of warped a flight plate only, then perhaps this could help; at least a little. But in my case the rim is also deformed, so I don't think that this would help. Al least not with with the rim deformation aspect. Maybe if I get the rim back into shape, and find that the flight plate is still wonky, then perhaps your suggestion might help. Thanks.