And I thought only the French were goofy enought to use quill seatposts........
Atax did make quill seatposts for a few Peugeot models in the mid 80's, so that could be an alternative for you if you want to move over to a more modern clamping system.....that's if they make the right diameter for your bike, .........and if you can even find one these days, they are getting rarer every year and the prices have gone up considerably.

Chombi