EMF lever action problem

[God Bless The Mauser]

My dad purchased a EMF lever action clone of the '92 Winchester in .45LC and has been having some problems with it. The action has been really rough from the beginning and had been getting worse so he took it apart and did an action job on it. He got rid of all the burrs and polished all the moving parts and it got worse, now it is REALLY hard to get the action open and when sliding the action if feels like there is sand in it. This doesn't make any sence because he did the same thing to one of the older clones he bought back in the '70s and it's really smooth now. Anyone have any ideas why it would get worse after the action job?