I removed the two guides beside the rear lamps for the hatch on my 945. There was corrosion starting under there and it was caused by very fine dust that had accumulated between the chassis and the guide, sanding the paint.
They are easy to remove and replace, no adjustment necessary.

There was also corrosion on the hatch itself under the aluminum bracket that enters the guide. These need alignment when you reinstall them and I don't know yet if it is difficult, or eye-balling is enough.

Hope this helps,
Mikael Larsson