VPI Classic motor question

See below, my correspondence with Mike from VPI on the re-installation of the brass collar after lubricating the motor.
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Mike,
I have a Classic 3 for over a year with the 300 RPM motor. I took the Pulley and brass collar off and lubricated the motor. What is the prescribed method for re-assembly of the brass collar on the motor shaft?

1. The motor shaft has about 2 mm of play, up and down, should the motor shaft be down when inserting and tightening the brass collar? midway? or up?
2. Should the recessed part of the brass collar touch the fixed part of the upper motor assembly?

I tried a number of positions for the collar. If the collar actually touches the stationary area, and you put your ear up close, you will hear the collar rubbing against the stationary area. When the collar is just barely not touching the stationary area, there is not a sound. Therefore I concluded the correct position of the shaft at rest is at its lowest point, and the correct position of the collar is barely not touching the stationary portion of the motor assembly. So the motor shaft is at its resting point, you put the collar on, and position it so it is barely not touching the stationary area. Turn the motor on and listen. If you hear it hitting the stationary area, you have it too low. Try again. Try and get it so it barely doesn’t touch. Then tighten the allen screw. Is this correct?

*********Answer from Mike at VPI

Close!

When installing the brass collar you lift the motor shaft up, drop the collar on, lightly tighten the set screw. Turn the shaft, if it rotates easily (forget the thumps from the coils and magnets) and you have very little vertical motion of the shaft you are good. You should have very little vertical play but still turn freely. Snug up the set screw.

Mike

Actusreus,
I took the pulley, brass collar off the motor, and cleaned everything up, after a year there was a little bit of dirt mixed in around the stationary area and on the collar.  This is the primary advantage of dis-assembly versus using the syringe method, the ability to clean the area.  I used a tooth pick to oil the top part of the Armature (rotor), adding about 2 - 3 drops.  Then I also oiled the stationary area, the bushing, and the Armature shaft.  I originally put everything back together as described in my email to Mike and left it like that for about 2 - 3 weeks.  I then corresponded with Mike, and received the method which I posted.  Essentially he is saying that the collar is needed to ensure the symmetrical position of the Armature within the stator.  That did make sense to me, since as I did mention, the collar is recessed to fit the stationary area on top of the motor.  Lifting up the shaft, lifts up the armature, which re-positions the armature in the stator.  It also in turn, puts a little bit of pressure, from gravity, against the collar as it fits like a glove into the stationary part of the motor.  I surmise, based on MIke's remarks, that it is important to have that little bit of gravity pressure against the collar.  This also keeps the armature centered when you have the additional sideways pressure from the belt.  
Ultimately I re-positioned the collar, exactly as Mike instructed in the email.  I put the shaft all the way up, then tightened the collar, so there was no play.  I then barely loosened the collar and allowed the shaft to fall a very, very small amount.  So right now there is an almost imperceivable amount of up and down motion on the shaft.  That is how I currently have my motor configured.  If I make any more changes, it would be to give it a little more play, but right now I will leave it as is.  Also, since I know the collar is rubbing against the stationary area, I will be very diligent about keeping that area oiled up.   
As far as "noise" coming from the motor.  I believe the primary source of noise is coming from the collar rubbing against the stationary area, however, I will say, that with Mike's method it is very uniform, whether the belt is on or off of the pulley.