Front wheel spacer rattles a wee bit after bearings were changed out. It's been a very long time (dragging my feet putting all back together) and I don't remember if it did prior to swap out. Are the bearings not seated all the way?
Not sure what you mean when you say it rattles. Is it the correct wheel ?
Did you swap wheels or remove the outer seal for the speedo drive?
Did you put in the same bearing size that came out?
If all correct and original I would bolt it all up and tighten things so you can check wheel alignment in the calipers and centering in the forks. If it is all good maybe take a video to show us what you are seeing.
Lol... yes that makes a lot more sense doesn't it.
If the spacer is too loose the inner races on the bearings will be side loaded and this is not good. Yes first try and seat the bearings putting pressure only on the outer races. You should hear the races change tone when you have seated them. If the inner spacer is still too lose then I would consider either adding a shim or making a new spacer. If a stock wheel then the spacer is probably be steel and less chance it was due to the spacer so look close. If it has an aluminum spacer though I have seen these compress over time and need to be re-shimmed.
It is not a problem as long as the wheel is still spinning freely when final assembled to running torques, if you find the wheel does NOT spin freely (no brakes ) then you may be side loading the bearings.
Now .... where is that coffee I so obviously need.