Hmm he's started to sound like me, three shafts in the last two years over here.
First shaft is still a mystery we tore pump apart and inspected everything couldn't not find a speck of anything, pump was seated properly on block and shaft was proper length
Second was from pump not being installed correctly (American craftsmanship at it's finest...product GES in Bedford, MA avoid at all costs), I have a main support girdle on and rather than make adjustments to get pump to fit knucklehead used longer bolts and tried to torque it flat. Never succeeded causing shaft to snap.
Third one a rocker arm broke sending all the bearings down into the motor, I could only fish out 1/2 of them but figured I'll gamble and keep running car since it's been like 2 degrees lately and just had motor put back together a month prior. I also figured bearings weren't going to get through screen because they're larger than the opening well aparantly one of the bearings made it's way down the discharge of the pump causing it to lock up.
So might want to check all of these things.