Did you move the pinion away from the carrier? How much did you move it? Backlash is way to tight for a used gears. I would set it up at a minimum of .010 backlash being thats its a worn gear and im PRETTY sure it would have never been adjusted before in the housing it was originally in. The pinion still needs to move away from the carrier still though.
Dont get fed up with it yet. After getting the pattern right you still need to get the pinion and the carrier preload right. Did you swap the pinion from the used stuff or use the whole pinion and pinion carrier?. Its a learning process for sure