are you meaning the primary terminal in the side? that'd be a spanner nut, look for "spanner nut tools"
I have a slot screwdriver that's been deeply notched in the center of the blade that handles those

Bill

Moved over to the Passing Lane

"When we tug a single thing in nature we find it attached to the rest of the world" John Muir
"When we tug a single thing on an old truck, we find it falls off" me
Some TF series details & TF heater pics & Rust-a-holics Unanimous parking lot