I've successfully greased the inside of the wiper assembly, by heating up motor cycle chain grease, which goes to the consistency of thick cream when hot then reverts back to almost solid like when cold, and pumped heaps into the drain holes via a hand grease gun with a plastic tube attached that you can curve up into the drain holes without removing anything. After it was done the wiper was as smooth as silk in it's operation.

The easy not quite as effective way.

Cheers George