The sleeve is a VERY thin piece of stainless steel, and goes on without any machining. I like to polish the damper snout thoroughly with a piece of emery cloth, and use a block of wood to tap the sleeve into place. Most sleeve kits come with a small tube of red LocTite to secure the sleeve into place. It will be a snug slip fit, or a very slight press fit, so some gentle persuasion with a mallet and a wood block will usually be necessary to install it. Don't overdo it on the hammering, or you'll crush the sleeve. Be very sure it starts straight, or it will buckle when it's about halfway installed.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!