Replacing casters on an old fabric cart

You may not know what an old fabric cart is but years ago in the garment plants they were used by each sewing machine table. Fabric to be sewed was placed in the cart and the sewing machine operator would take out the fabric and sew on their machine. After finish sewing, they would place back in the cart, which was then wheeled away.

My sister has two of these old carts she uses for storing dog food bags. The concrete floor of her garage was rough and the old casters did not work well. She asked me to replace them with new ones. It turned out the old frame had to be cut off and a new frame made for the new casters.