The door windows have been removed in order to make it easier to spray and to clean up the insides. The mechanisms have been in place for years and the grease has been contaminated and gone hard. In fact the plastic guides that sit in the rails has broken.
I removed all the old and hardened grease by a scraper and then used a paint brush with the POR Marine Clean to remove the remaining grease. I used a nylon cleaning pad to rub the stubborn parts off. The left side mechanism was in a much dirtier condition and took a fair bit more cleaning. The left on the other hand was only about half as dirty. On the bottom of the arms there are three plastic guides that sit in the rails. These are removed very simply by pulling out the retaining pin at the bottom and lift off the guide. Once cleaned they can only go back on in one direction and the pin simply pushes into place.
Once the cleaning was completed the mechanisms cleaned up pretty well and I was pleased with the results.
The final step would have been to grease up the mechanism. But as this will not be fitted for a while yet putting grease all over the mechanism could be contaminated and make it difficult to handle. So I sprayed it with a good dose of Gibbs Brand Lubricant. This will stop any rusting and will penetrate and kill of any rust around the pivot points.
the only difficult part about this was getting the mechanisms out of the door in the first place.