You should be able to do it yourself. The first thing to do is mark where the nut is-- in relation to the pinion shaft. A center punch will work.
Now remove the the yoke [balancer] and seal. reinstall and tighten the nut to the exact place where the nut was before-- a tiny bit tighter will be OK, but never less than before. You can check the rotating force before and after with a dial torque wrench.
People mess up doing this-- by using a impact wrench and over tighten, or under tighten the nut. The torque on the nut, loads the pinion bearings.
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