Without knowing what machine we're dealing with, it's hard to say how to set the columns, but if you could post a picture of the front of the machine & the inside ( full frontal
) someone might be able to identify it & help you out.
from what I can see of your columns, the front gate just keeps the cans from falling out the front of it, there should be a back spacer that should be able to adjust to allow for the depth of the bigger 16-oz tall boy cans. as for the smaller 10-oz cans, you may have to shim the sides of the columns to take up the slack (make the column narrower) so they dont get stuck side-by-side at the bottom. but once its shimmed, it sould vend the small 10-oz cans too.