I'm positive thats not a 1973. its an early 90's probably Tomos Targa. look at this one
http://www.mopedarmy.com/photos/brand/58/653/
its got the a35 engine on it (50cc). its super easy to find parts for. you can get every single thing for that bike down to the smallest screw from Mopedjunkyard thats where I've been getting my replacement parts.
http://www.themopedjunkyard.com/newtomos.html
whats not working on the bike?