Here's where the serial number is. Looks like numbers are visible, but will take some good wire wheeling to get a better view.
Several rounds of wirewheel brushing, then degreasing and rinse, wirewheel again, degrease, rinse, repeat, repeat....
It takes time, but they do get clean. Here's how a nice can A&H look all thoroughly cleaned after 100 years, this later serial number is on the opposite side on the front foot.