Starter Motor rebuild Ball bearing size?

Hi All

I have been rebuilding my Starter Motor following Joe’s excellent video, the problem is even with the tips in the video the starter motor fell out of the vice and exploded on the floor, I have found all the scattered internal parts except the ball bearing the that Joe said “Be careful not to loose this”

This is the ball bearing that goes on the end of armature when it is mounted into the body.

I’m sure I would be able to source a replacement if I could find out the diameter of said ball bearing.

So if anyone is rebuilding their Starter motor and would be prepared to measure the diameter of the ball bearing and let me know that would be really helpful

Thanks in advance of any help