According to this article it is suggested to remove the spacer in its entirety.  Has anybody done this?  The reason I ask is that my wife's is still just a tad lean at part-throttle inputs so the needle needs to come up a bit.  Right now I have the stock white spacer down to half thickness.

"Getting back to your Savage 650, Coney, here's how we can specifically cure its problem. We need to richen those two areas of the curburetion curve that are factory set on the ridiculous side of leanness. Remove the diaphragm slide from the carburetor and look down inside its bore. Two small screws hold a plate over the slide needle.
Removing the plate, you'll see a small, white plastic spacer with a hole through it sitting on top of the needle. Throw that spacer away and reinstall the plate. A spring under the needle clip will now push the needle up to the plate occupying the space vacated by the white spacer. The distance that the needle has been 'lifted' is the thickness of the discarded spacer - and that's ideal. With the needle raised, more fuel will flow by it, meeting the actual needs of midrange running."

http://bruceclarkemexico.tripod.com/ls650.htm

If you have an ACE HArdware nearby,.. a #4 teflon washer is equal to .6 of the stock one and fits perfectly.  They can come in black or white
(very fashionable)