If the shaft does not spin freely you will need to remove the drive plate (one or two grub screws) and pull the shaft out, clean all the old oil off and re assemble.  On the ones I have done the scaring from the grub screws had to be filed down to allow the shaft to pull back through the bearing.

One thing that is also worth checking while you have the unit apart even if the shaft spins freely is the grub screws holding the drive for the wiper plate.  If these are anything less than very tight the wiper will move on the shaft relative to the cog on the back making adjustment impossible.

When re assembling ensure there is a small amount of front to back play in the shaft so the unit does not bind.

Excellent pictures and step by step.

Michael