PTO Shaft Problem

The CV joint on the PTO shaft of my Bush Hog 2615 shredder was going bad, so I bought a replacement shaft from Sloan Express.  This is a 21 spline 1000 RPM shaft

 

The 2615 end went on -- no problem.

 

The tractor end of the new shaft will not go on enough for the locking balls to seat.  I cannot get the female end to go any deeper.  Looked inside--there is an-ever-so-slight ridge by one of locking balls.  

 

I'm wondering if this is a manufacturing defect or if the clearances are that tight?  Any thoughts?  I have used the 1000 RPM PTO with the old shaft--no problem.

 

Thanks,

 

Ralph

PTO Shaft Problem