Hi llewes,
Once you’ve got the machine set up right for golf balls– with the pen motor and pen arm in the right position — you shouldn’t need to do any additional adjustments to the machine itself. The only setup that you really need to do is to remove the balls and put the next one in.

The technique that we use is as follows:
(1) Put the ball in
(2) With the motors disabled, spin the ball around about one revolution, looking at the top edge of the ball as you spin it. As you spin it, note how much the ball goes up and down.
(3) Stop when the ball is highest, so the “high point” is pointing up.
(4) Keeping contact with the tail coupler, lower the ball against the egg coupler (the side facing the motor), half the distance that it wobbled up and down.
(5 — optional, while getting started) spin it around once more to verify that it’s centered.

Once you get the hang of it, that can take about ten seconds.

The abrasive grips on the two couplers are made of a type of memory foam, which will slightly conform to the shape of your ball with use. That conforming will help to get your ball initially centered as well. I’d suggest that if you’re only going to use golf balls, to store the machine with a golf ball (centered) in the mount, so that it’s ready to help guide your first ball of the day into position.

No, I’m afraid that we haven’t seen those before. They appear to be standard rubber grommets that you could get from a company like McMaster-Carr.

The dimensions of the couplers (and spares, without the abrasive foam attached) are available on our store pages:

https://shop.evilmadscientist.com/productsmenu/709
https://shop.evilmadscientist.com/productsmenu/754