Shift boxes are a very poor quality of "pot metal" (aluminum alloy) and are prone to wear and misalignment of the shift rods. The two halves of the box can be file-fitted and shimmed to restore the alignment of everything if they're not allowed to deteriorate too badly or break before being repaired.
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!