Furnace cover screw replacements

[DonnaDuane]

I've noticed that several screw holes are stripped, and the screws are very rusty from exposure to the elements. Can anyone advise me on how to fix existing holes, or get slightly larger screws that are less likely to rust. When screwing into fiberglass, is it necessary to tap the holes, and should I use some kind of thread lock?

 

Thank you,

Duane