nrp wrote:

I found some small wire brushes about 3/8 inch dia that could
be chucked into an electric drill and slowly rotated in the threaded
hole to clean the crud out of the threads.

Probably .30 caliber rifle cleaning brushes.

George Patterson
Give a person a fish and you feed him for a day; teach a person to
use the Internet and he won't bother you for weeks.