I need to enter the attic via this gable vent hole, unfortunately I can’t fit. My thought is maybe I should install a 2x4 against the (what I assume is original) lighter colored beam to the right, and another for good measure at the left side of the hole.
thoughts?
Totally understood. From the looks of it, neither 2x4 is properly bearing weight. Placing new, non-cut, 2x4s on either side of the opening and tying them together with a sill plate is probably better than what you currently have.