Center shaft...question

[Panic]

I m cleaning my pred x11, and I noticed that as i spin the center shaft by hand it doesnt turn smoothly...in fact in a specific point almost stops and you need more power to turn it. No tires on the car ,no motor , and everything is just rebuild , diffs are ok , no teeth missing from the bevel gear or crown .Also i have shimed the shaft to stop the play which had from factory. Anyone has any idea wht i might causing this bind ?