[66sprint]

Duh. I forgot about the guide pins on the accessory housing. The main gasket has to be adhered to it so it can slide.
If it was glued to the block would not work.
The last time I replaced the gaskets I think I used copper coat as recommended.
But I remember some suggestion to use Pam on the sliding side.
I don’t recall if I used a little grease or it went on dry.

And thank you for providing accurate information and helpful advice.