If the system requires more torque now than in the past, something is changing. What's changing? The number of pinion gears did not change, so how will increasing the number of pinion gears solve the problem? Something else is changing. Something is creating more and more friction in your system. What are the possible sources of friction? Maybe the alignment of the pinion gear and the bull gear is not right, and one of the gears is wearing away. Do you see a collection of steel dust anywhere?