[Yoda]

It has never been made clear to me which tricept muscle('s) are active for EA.

Just as bicept curles can be performed pronate or supinate so and use DIFFERENT bicept muscle, A tricept push down can be done pronate or supinate and use DIFFERENT tricept muscle. One way creates no control but great tension the other creates "structure" and frees the wrists and power package from tension. Which does what and how is EA properly applied. This requires more description than "stretching" . HOW not WHAT.? I believe this is KEY.

Uh . . .

How about . . .

Stretch the left arm in the direction it is pointing?

That's what should be done, and it is what I do.

Is there a specific right triceps muscle that does this? If so, please spare me . . .

I don't want to know!