Tough one if you don't want to re-rivit. Leaving the sockets on will make it hard to make it flat as you really need to be able to press the plastic between two things that are flat so that it stays flat when it cools. Seems like glass is the item of choice. With that you would have to do it more manually. Only thing that could get hot enough would be a head gun but you would have to be REALLY carefull.
I can't imagine their is a lot of vibrations in that piece. I recommend removing them and re-riviting. I know you don't want to but only way I can see to make it right. Plus you could use some of the pressless rivits if you don't have a press.
Denver, CO
