 I would go ahead and repair the loose mortar where it exists. But in terms of the reinforcement, I can only imagine how many different opinions you're getting here. But the only opinion that I think really counts is going to be the one that comes from a structural engineer because, and here's a really important point, no matter what you do to fix this, if you don't have professional direction on this, it could potentially impact the value of your house. If you've got some serious cracks like that and you're trying to address that and make sure it doesn't happen again,