Another Collimation Question

I placed a very small dot (using white out) at the center of my secondary believing that lining it up with a cheshire would be made easier. It also aligns very well with a laser. I can see the laser hit the dot (using a hand-held mirror) and hit the center of the donut.

But when I collimate my primary the dot does not appear inside the donut. It is just out about halfway between the center of the donut and the edge of the cheshire tube.

It could be I have not found the exact center of the secondary. However the previous owner had placed a very small black dot on the secondary that I took to be the center. I used the white-out to see the dot better. It measured out close enough to be the center.

I've read about optical verses mechnical alignment but I'm stumped. I would appreciate some help in understanding whether or not the dot should appear in the donut for the scope to be properly collimated. Or is this evidence of the proper offset I've read about. The scope is a Coulter 13.1 inch f4.5 with the original secondary.

Thanks

DCR

If I remember correctly, the Coulter has only minimal collimation adjustments - one of those frustrating push-pull mirror cells and a thick and heavy bar type 2 vane "spider" that has zero provisions for offsets unless you drill out the bar. So, with this in mind, just basic collimation adjustments can be a challenge on this scope, let alone trying to insure offset of the secondary.