both mirrors have up and down adjustments for mirror but neither will rotate left to right on the posts to adjust for proper side vision.
what is the secret to making them adjust in this dimension?

Take them off the doors and there's a locking nut at the bottom....loosen it and walahhhh. Rotation.

They get corrosion inside so take them off., loosen nut and drip penetrating oil at every moving spot and on the nut.

works every time.

Trying to make it move without removing the mirror/bolt and you wil break the mirror.

Don’t force them. It just deforms the stainless mirror back. They use internal springs to keep the correct tension but after 50 years, most are corroded inside. If you take them apart, lube them up, they will work like new.