I was touching up the black enamel on the Bravo 3 outdrive and I noticed that the 2 upper left nuts holding the stern drive on had corrosion around them. The lower of these 2 (middle left side) has the continuity screw. Broke the head off the continuity screw while trying to remove it.

Clearly, trying to drill out a hardened stainless screw stub in an aluminum case would be a nightmare. Can I substitute a stainless lock washer UNDER one of the flat washers? My reasoning is that the lock washer under the flat washer will break through the paint to the aluminum and restore conductivity. I would also put electrical conductivity grease there to protect the contact.

If the lock washer is not good, what would be the best way to go?

Thanks in advance for any help!

As long as its grounded its fine. Or drill and tap a hole next to the screw you broke off.

Yes, I did check and the outdrive is grounded somewhere else. Good suggestion, Just tilting the washer provides a new location for drilling and tapping a hole.