After speaking to a very knowledgeable S2 engine builder, he hinted that the balance shaft covers were swapped, and he was right. Both shafts spin nicely now and each have a fresh set of bearings as well.

Now I really don't feel very smart anymore.

 

That makes two of us...

 

Well, the engine build goes on. More info in the other thread:https://rennlist.com/forums/6446390-post32.html

In fact, there is a question posed for assistance on a part identification.

 

New Sit Rep available here: https://rennlist.com/forums/6497145-post40.html