Not sure how they got so bad but almost all of my door clips and the cup-like plastic receivers that secure them were toast. After ignoring this problem for a long time, I recently found perfect new OEM pieces on ebay, from Germany. The vendor is 'fiat-parts', just search "Fiat, Lamborghini clip for door panel".
Amazing these are available ~50 years later but were apparently used on various Lambos, Fiats, Alfas etc at that time, so it was not an uncommon part. Here is what came in the mail: