Getting a ceased screw out of fiberglass??

*Seized. Not ceased ](*,)

Hi, this is a great forum first off. I love it!

Here's my problem. I just got a 1973 Duster with a fiberglass spoiler on it. The fiberglass is in perfect condition. The metal mounting brackets and screws which allow you to choose the angle of the spoiler are not. They are completely rusted, there is no bare metal. When I try to unscrew them they either round off with very very little torque, or they will not budge :thebirdm:. Most are to the point that I'm sure they'll break if I torq any harder.

My delimma with getting ceased screws out of fiber glass is;

1) Will PB Blaster harm the fiberglass?
2) I obviously can't freeze or heat them without damaging the fiberglass

Is my best bet to drill these screws out? There're 18 of them...

Also would an impact screwdriver work? Or am I just asking for trouble with one of those?

Cheers!
Drake