Shaft breakage could be related to improper torquing of the far end stands. I broke a shaft early on with my original motor and discovered, sure enough, the correct "procedure" had not been followed BEFORE it was torqued. There is an adjustment to get all the clearances taken up, THEN you torque it.
Sure sounds like an oiling problem on the push rods, if so, it likely wouldn't matter what brand your using if there not getting
oil.