Absolutely original parts for a LeTour III, would be hard to acquire, but not impossible. To me it sounds as if the seller used either really cheap, or old cables--- OR you have been riding a modern bike with index shifting and V brakes. If this is your first experience on a 30 year old bike, there is a world of difference, especially if the cables are cheap and the brakes were not set up correctly.

My guess is you need modern compressionless cable housings, new coated cables, new brake pads, and new aluminum rimed wheels (if the original steel ones are still on your bike). BTW, do you have the blue or the orange model? I love the orange! Best of luck!