Use a 3-corner file to clean up the internal splines on the Pitman arm. The splines on the sector shaft are tapered, so creating a looser slip fit as the arm is installed will self-correct as the nut is tightened.
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!