Yes, more of a rotational positioner and not for vertical support. I think of it more as a guideline, as I find it fits my setup best when NOT in contact with the rubber spacer or the way tube. But, my setup is not typical ... I use a blade with 5/8" arbor most of the time, which is longer than the 1.25" blade arbor. And, I extend quill slightly to start with so I can fine tune blade position either to left or right. Extending quill slightly avoids lower guard rubbing on headstock. And, I keep the 1.25" aluminum spacer permanently mounted on the lower guard.
Out of curiosity, I found what the original instructions had to say about installing it:
