Hi Art.

I found that a long (16" ?) 3/8" socket extension made a great probe extension for reaching the terminals on the starter with minimal voltage drop or frostbite.

My theory is that the scuffing on the body of the core was dragging on the inner bore of the solenoid when the temperature started to drop. The core was a stiff push into the solenoid at 50°F. Cleaning up the scuffing with 400 grit wet or dry and polishing the inside of the solenoid produced a smooth sliding fit. So far so good.

It might be that the drop in temperature that tightened up the bore just enough to seize the core. Once the core was as cold as everything else the grip was released. Testing is the hard part. It is going to dip into the mid minus teens later this week, but if the car starts (which is my hope), it does not prove anything.

Greg