Re: Replacing posts under beams
I would also agree that you need a more substantial footer under that post.
As an example, the two posts in my basement have a 2' x 2' x 2' footer under each, they support an I beam that supports the structure above. The same for the three posts in the detached garage, 2' x 2' x 2' footer, the posts support a triple 2 x 12 which is the beam for the upstairs.
Similar to what you presently have, the garage beam is also supported by a triple 2 x 4 post in the wall between the garage and workshop which sits on a double plate that is on 3 courses of block that is concrete filled 2' on either side of that post.