There are many youtube videos on the subject so I am not going to go into the how to portion of it.

I will say that what you want to do is to slowly tighten the allen bolt until you feel resistance.

The back it off anywhere from 33-45 degrees.

Next tighten the nut nice and tight.

Then road test it, if your steering wheel doesn't return to center when you take pressure off of it going around a curve, it is too tight.

Simply loosen the nut and back off the allen 5-10 degrees and repeat the process.

This will only tighten up the gearbox, and should only be done when you know you have play in the gearbox itself.