I knew very well that the spacers add a noticeable wobble or v o.oibe before installing them, but this can generally be remedied by tuning. My question is…How exactly do I tune it? o.O’
Rotate the axle around until you find the best position. You can try it with the nut too.
Like this:
Enjoy.
Thanks a lot you guys, I’ll definitely give this a try 
Also, at what point do I stop tightening the gap? With the longer replacement axle, it seems to just sort of keep turning. It does get to a point where it doesn’t look like the gap is getting any smaller, so I want to think that it’s good to go, but it’s just so weird to not have a yoyo tighten firmly into position.
How tight is tight enough?
Tighten it down to take up all the exposed axle. Then use your palms to hold the yoyo. Twist it with just your palms until it starts to slip. Then just snug it up just a smidge.