distributor cap screws rusted
 

'87 420 sel---- can get two screws out, but third is rusted or something and won't budge more than a millimeter or so. don't want to drill it out if not necessary. Anyone had any experience with this? 139k miles and probably needs replacing. HATE to have to buy a whole new distributor.
Thanks,,,Art

Try liberally spraying PB Blaster on the screw. If it's badly rusted let it soak overnight, spray the area again then try to loosen it.
Colin.