I am fixing a bench and came across the above mortise and tenon joint between the foot and the vertical support (2 actually, one on each support). Quite clearly, someone has messed with this joint in the past cutting down the tenon so that it is about 1-1/4” too short on its length and 1/2” too short on its depth (they also added a screw into the end grain of the tenon, presumably because the joint wasn’t strong enough after they cut down the tenon).
Obviously, I have to fix this in putting the bench back together, but I’m not sure if I should approach it as adding to the tenon or filling the mortise to make them match. Which is the better option, or is there some other way that I haven’t thought of?
Edit in response to comment asking about tenon thickness: The thickness of one tenon is what I’ve always thought is perfect: dry assembly requires no persuasion, the joint holds together by friction alone against gravity, and yet can be shaken apart with one good shake. The other tenon is 3 sheets of copy paper shy of that point (i.e., by placing three sheets of paper alongside the tenon I can get to the same degree of tightness).