I'll post more later but in the 12 scale I did not have any problems with the 3 pinions. And I ran about 250-300 laps so if there was a problem I should have found it. The x-ray I have "other" issues and did not run the PRS gears.
I think Tony may have pin-pointed the problem with something being a little off in the drivetrain, motor not quite straight, something in the center layshaft, mayb e even a bent/broken rear arm that caused the rear diff to "lean" to one side....
Thanks for all the help and I'll post more info after I run these on the x-ray....