m_corbelli wrote:
I have a house that's now 18 years old. I am the original owner. On one
circuit, I am getting intermittent loss of full power. This is manifested by
lights that go dim like when a motor somewhere kicks on...


This sounds characteristic with a problem that manifests itself with
"backstabbed" devices. These have a small contact area in comparison to
screw terminals and the spring tension may vary with heat. You may want
to rewire each device using screw terminals.