PS - I just got that mount straightened out today. That's why I hadn't advised you all earlier. I should mention with shame that vice-grips were used, but did no damage. it was the only thing I had that opened up to just the bite I needed to re-close the split shaft pieces to the correct size. I'm now wondering if someone had jammed an early Pearl mount inside at one point and then found they couldn't close the collet on it. The drum came to me with no collet even though all the other parts were on it.

Hi Dan! Glad you got it figured out! The "split shaft pieces" you are referring to is the "collet". The "collet nose" spins down on the collet to lock it. You are probably correct in assuming that a Pearl arm may have been inserted, forcing the collet pieces apart.

-Mark

Ah, a very good correction on the part names. Thank you for that Mark. I've had that wrong for a long time. It's good to finally have the correct terms in mind.