Check the spindle closely with the nut removed. There is usually more than one hole for the cotter pin, which allows you to split the difference between castle nut slots. The holes are at a different angle than the slots, 90 degrees apart instead of 60, IIRC. If there's not a second hole, drill one.
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!