I’d plan on replacing the foot control, just for my own peace of mind, although some of the new ones that I’ve seen retail for over $100, so that might make me gulp.
Wiping out and drying out the older machine and re-lubing it should save it. Then run the heck out of it to help the oil and grease displace any moisture that remained.
I’ve brought some rusty old machines “back from the dead” that had rust all over them, but that incurs a certain amount of disassembly, cleaning and reassembly.
CD in Oklahoma