Originally Posted by
kunsunoke
Velo Orange is your friend. You should be able to get replacements for French parts there - including brake pads and brake hoods.
Randy is right about the Simplex derailleurs - they're likely to be trouble, due to the effects of environmental degradation, time and ham-fisted wrenching on the Delrin. Inspect carefully and replace as required. By the way - the rear derailleur drop-out is Simplex-specific. You can switch to a threaded rear derailleur, but you will have to thread the drop-out hole with the appropriate tap - and also modify the drop-out using a Dremel or similar grinding tool to take a B-screw. Yes, it butchers the bike. It's either that or risk having a mech come off while pedaling.
PX-10s have "death" stems. These got their name because the French manufacturer failed to prevent crack propagation - so some would snap in half at the worst possible moments. The death stems have to be replaced by French 25mm specific stems with proper stress crack relief - or swapped out in favor of carefully-sanded 22.2mm Nitto or SR quill stems.
If the bike has tubular tires and wheels, keep them. One of the pinned threads in this forum is about tubular tires - or you could just ask us for recommendations.
Yeah, fix it. It won't be hard. We can talk you through this. Don't butcher the derailleur hanger--just install a decent Simplex rear derailleur. They're not too hard to find. Someone here will probably sell or trade you for one. Apart from the sentimental value in your case--which is substantial, it seems to me--the PX-10 is a great bike that's really fun to ride. Add my voice to those requesting pictures.