On my QL 114, three of the four screws holding the ballast door in place are completely seized up. The one I was able to get loose with some effort, but the others are completely stuck. Even after applying WD-40, they still won't budge. How do I go about loosening them?

I know heat can help, but be careful with that...

Careful application of heat, either with a heat gun or a torch can help. A stronger penetrating oil such as PB Blaster, applied in conjunction with heat will also help.

I know heat can help, but be careful with that...

That's the thing I'm worried about, I don't want to apply so much heat that it damages the paint.