For a pin I just made a crude piece out of a 6mm bolt which I cut to desired length and then filed a flat spot where the screw will press it in place so it doesn't slip when turning. You can get a 6mm aluminum rod at Home Depot or other hardware store for about a buck, which I think is what I'll do later today just to make it a "nicer" pin and will look for a "nicer" locking screw for a better match. This is so trivial though that it does't really matter since you can't even see the pin - I just like knowing it looks nice
As far as AZ circle being a slip circle - yeah, both AZ and ALT are the same mechanism, they operate with a clutch.
$800 is no small chunk of change, but so far, after using the mount for about a week pretty much every night I'm quite happy with it. I'm enjoying manual slo-mo tracking and pushing far more than I thought I would. As far a good balance between portability and stability I couldn't have asked for more.
Following your lead, I ordered the Vixen flex cables for my AZ8. I went to Home Depot this morning to purchase set screws and 6mm square rod, but with the help of a saleperson we couldn't find any rod (square or round) that would work. I wandered around the store hoping to be struck with inspiration and in the electrical section found some butt splices that I thought would work.
These are the items purchased at Home Depot:
Butt splice securely attached to AZ8 slow motion knob with set screw:
Vixen flex handle securely attached to the other end of the butt splice:
AZ8 ready for action:
This setup works well in the comfort of my
astronomical instrument setup room breakfast nook. Will be trying it under the stars (hopefully) at Cherry Springs later this week.