I found a nice 60's Olmo abandoned at work, built up with 80s touring parts. (I got in touch with a previous owner who said he sold it to an intern, who probably abandoned it when he left).

I've been rebuilding it. But getting the Duopar set up right after putting it back on is confusing me since it's not like other derailleurs I'm used to with the pivot at the hanger. Just tightening it down doesn't seem to work since it'll come loose in certain gear combinations.

So how do I bolt it onto the hanger correctly?