First off, I am very new to bicycle culture/maintenance, so please, go easy.
I just bought a bike (1974 Peugeot 10 speed according to craigslist add) for $100 so that I could have a road bike that was in working order, but had room to improve/upgrade/learn on. I have successfully replaced the brakes and adjusted them to my liking (go me), and now I am working on swapping out some friction shifters that are mounted on the downtube with some ones off my old junker that are mounted on the handlebar stem. Obviously cables from the old shifter mechanism were too short, so I salvaged the cables from the handlebar stem which seemed to be in better condition anyway. My issue right now is that while I can shift one way (towards the smaller gears, up, down, whichever direction that is, sorry), the tension isn't released when I want to shift the other way. The old shifter mechanisms worked, so I'm thinking maybe it's the cable? Also while researching I discovered that the housing for the shifters appear to be brake cable casing instead of shifter cable casing. I don't know how big of a difference that makes. Also, the casings don't seem to have barrel adjusters. I did, however, lubricate the cable with some 3-in-1 where the cable goes through the casing.
I can post pictures if necessary