Any movement at all between the gear and the shaft is too much. Replace the distributor. Sometimes it's possible to drill a larger hole and use a bigger pin to take the slack out of the assembly, but use a solid pin (not a hollow roll pin) and rivet it to be sure there's no slop. Driving the oil pump puts enough stress on the pin to wallow out the holes if there's any movement between the shaft and the gear.
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!