Hi Pops
I used Summers Bros gear drives on my customer engines and they were a great product
During the set up on a new unit the backlash was set, and the crank was turned to look at something else and for grins I checked the gear lash and no Clink - Clink
Back to top center and it was fine, turns out the cam gear was out of round
So Bob sent me a few more gears to check and they were bad, had distorted in heatreating and they had made 100 pcs [ they were not happy campers ]
Maybe one of your gears might have been that way too, and loaded the bearing in the tight spot
After that I always checked for the Clink= Clink in several spots of crank rotation to be on the safe side
G Don