It works!

The new bearing that I made for an antique great wheel works! It is slightly longer than the original, but since the maidens adjust separately, the fraction of an inch difference doesn’t affect functionality.

Photo description: my hand holding the original bearing on the left and the new one on the right

The shaft of the bearing ended up being a little thick. It was a tight fit, but needed to be able to rotate to hold the accelerator wheel as the maiden post was twisted up or down. I used my pocket knife to shave off some of the wood so the bearing could rotate.

Photo description: bearing with the shaft narrowed held in my hand next to the maiden post, spindle visible below
Photo description: fully assembled accelerator head on a great wheel with new bearing on the left side of the picture and the original bearing on the right

I spun for about an hour, working on my yarn width consistency and testing out my new part. It worked just fine! And rotated in the socket when it came time to stop and release the tension on the drive bands. I always lighten the tension between spinning sessions so the bands don’t stretch. I don’t loosen them enough to come off when stationary, which is standard practice for spinners. I can see though, how someone coming along and turning the wheel might be startled by the drive bands coming off or the parts not moving. The bands just need to be tightened before use.