Proper gear adjustment?
 

There's been alot of post about how to adjust the motor gear to the mech box but I was wondering how do you know when it's properly set?? Sorry if it's a repost.

When it's at it's quietest. Simple as that.

One way has a low pitched whine, the other way has a high pitched whine.

Don't force it in too much, or you risk burning the motor, don't let it back off too much, or you could strip your pinion & bevel gear. You just have to find that "sweet spot" with your ear.