There should be a circular band with two holes that line up with the existing holes. Beater rod inserted into circular band and tightened by a bolt/wingnut running through the matched holes. Several samples can be found on reverb.
I just wanted to add that your clanger is also designed to be able to switch off the clanging "function" by reaching down and lifting up on the striking portion so that it doesn't always strike the cymbal. The cymbal is usually mounted on the right side hoop of the bass drum so the clanger swings from the right side of the beater shaft. I keep my hinge loose and put a little oil on it every now and then. It works best for me with an old fashioned beater ball. I can recommend a marshmallow beater from Creative Percussion. Cheerfully ignore if you already knew all of this!