Rear blind dramas

Yup.
Take apart the whole shebang. Degrease. Grease. Refit.

Reinhard

Here is a link to a post in the German section with images: >LINK

Seats and side covers have to come out, unless you have foldable rear seats.
(On the other hand, even then, removing them makes it easier to remove the side covers.)
You should try not to remove the C Pillar covers tough. (In contrary to the images.) The fixing tabs brake very easily and it's not really possible to repair them.
It is possible to remove the self without removing the pillar covers... it's just a bit fiddly...

Shelf in the front is held by clips. After unclipping them, slide the shelf slightly forward. Push the top of the sun shade gently trough the opening and slide the shelf forward.
The sun shade is held by two screws underneath the shelf (accessible trough the boot).
Disconnect cables.
Clean and grease the rails.
Connect cables and test if it works. (Hold it by hand or put the screws back again).
When putting back the shelf to it's place, take care that the tabs at the rear go back to their place correctly (otherwise it might rattle).
Now that's a real pain with the pillars still in place, but it's possible. Take your time there.

Is your car standing on the sun a lot? That might caused the color change of the shelf. Not much you can do about it besides replacing it or putting new fabric on it.
I don't know if re dying would work or if it would dissolve the glue underneath the fabric.

Cheers,
Steve

Textile colour will do the trick. I have no idea what application form is best. I guess dissolve in little water and then brush on until satisfied with the result.
Has been done this way before and results were satisfying.

As Steve pointed out there are only a few screws to remove that hold the rear seats in place (pre 9/92). I seem to remember that they´re only accessible once the side panels have been removed but quite honestly can´t fathom which one goes first.

The parcel shelf has 4 long white plastic clips on the front end (post 9/92) which are plugged into the shell and have to be moved upward for disassembly. Again not sure whether the same applies for a pre 9/92 car - methinks there were two screws holding the shelf in place.

And indeed the C-pillar covers are somewhat fragile esp. on the top end tab and are best left in place. Removal of the parcel shelf will work as described above and reinstallation with C-pillar covers in place may turn out fiddly.

The reason for the sunshade not working properly anymore is just grease turning into glue over the decades. In addition to that a problem can arise which´d require the replacement of a toothed gear in the motor. This is the case when continuous ratcheting is heard upon folding it in.

All said this is not a difficult job and the degreasing may also be possible with brake cleaner in situ but certainly more effective and healthier for your back if taken apart.

Cheers
Reinhard