The OP is referring to the flat "bar" that comes out of the diaphragm area....that's what he's calling "the plunger". This has the hole in the end where it attaches to the plastic flapper door.

On the vacuum motor he has the bar needs to be oriented up/down so it sits flush against the tab part of the flapper door....so the flat bar needs to be "rotated" somehow 90 degrees.

It's a cool piece and being a real/original one it will likely last. I keep hearing reports of the diaphragms going bad on repro units but not sure if that problem is super common or not.

 

I had one of these and was able to turn the rod. I can't picture exactly how I done it but I was able to do it. Was about 5 years ago so I would have to look at one again and think about how I done it.

 

 

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