I've been watching the 1947 movie with Gary Cooper & Ward Bond (Unconquered) and at 1:20:18 into the movie, Ward Bond hands Gary Cooper several wood ball blocks on a rawhide string just like we use today... I'll post a link at the bottom.
Anyway, ball blocks in a 1947 movie that is set in the 1760's doesn't actually prove that ball blocks were used, but it does knock off close to 70 years of guess work (1947 - 2020) bringing us a bit closer to the answer if they were used in this 1760's setting time period? I thought it opened some doors for some thinking on the subject as Hollywood even back then at times tried to be authentic, maybe more so then today's movies...