Rear view mirror...

 I have put the dashboard apart. Early DS always have their mirrors going bad...

... here is why:

I've bought a cheap mirror at Walmart and will make a new mirror. I usually brake two before being successful. The original mirror is 2mm thick; bathroom mirrors are 3mm and I use them for the later DS21. Here I cannot use 3mm since it has to fit in the grove and the glass fro the day/night settings have to fit on the top of it.

Once I've got  a rough shape I grind the glass up the the dimensions then I fine tune the corners with the old mirror attached to it.

I use a belt sander to grind the glass; first with a heavy grid then with fine. The mirror is finished there.

Finally I'll be able to see behind me.