Found my instruction sheet! And the answer is..... "NOTE: Apply RED Loc-Tite to threads on shaft. Torque nut to 22 ft/lbs or 30 N/m".
Hope this get's you fixed up. I sure hope he put the spring washers and stuff back on in the correct order and orientation... it's all gotta be right or else. I wouldn't ask him, I'd just watch him and if he puts that nut on the shaft without cleaning the threads (with acetone or something) and/or doesn't put some Loc-tite on the threads and then just tightens the nut down "tight" with a standard rachet or end-wrench, then he's BUSTED! He should have an adjustable torque wrench on which he has to set a dial in the handle to the correct torque, and then he should tighten the nut till the wrench audibly "clicks". That's when the torque is correctly set. Sometimes most of us will pull just slightly on the wrench a time or two more, hearing it "click" each time again, before calling it a done deal.
Good luck and hope this fixes your problems!
- Michael