I cut up,mince, or grind dry castor, and reconstitute it with sac oil, I wouldn’t want it to work better as I can’t keep up skinning as it is.

it's a lot easier to just open up the green castors and scrap out the contents and add glycerin or mineral oil to make a paste.
The sac that contains the actual castor is of no value in making the lure.

I have stopped adding any bud oils to my spring beaver lure as it tends to attract unwanted muskrats because our season is closed.

This. Unless I decide to buy a bottle of Paul's Backbreaker, which I used to use for multiple species in Alaska, I do what Beav says, here. In fact, the last beaver i set for, I dug out a set of castors from last year that had been 90% dried and put in a zip-lock and into the freezer. I couldn't find my bottle of Backbreaker so thawed out the castor, scraped out the castor itself, and not having any glycerin on hand, took a tablespoon of Vaseline and melted it to a liquid with a heat gun on low, then mixed in the castor.
This was this last December, and I made a single castor mound set, and the next morning had a giant 70# beaver. And that was far from the first beaver to fall for a plain castor lure, for me.