btschumy So unless the 8 mm shaft is actually covering a smaller shaft inside it, it looks like I will need to order a new, larger coupler.
Hi Bill, I just checked the stainless steel focuser shaft on the FOA-60Q, and sure enough it is 8mm in diameter. So a Tak standard.
I checked my past Amazon orders, and there is one for a 8mm coupler:
https://www.amazon.com/gp/product/B08LM9DLY8
So, that must be what I have done.
Sorry for the confusion.
Chen