I don’t know if this will help, but I had to resolder the cables to the bed of an old printer and the iron I had just couldn’t put out enough heat; the bed sank it all. I put it in the oven for a while, so that it was pre-warmed and the iron could melt the solder.

Probably using the kitchen oven where I cook wasn’t a very good idea, but hey, I’m still alive.