I know your problem. I have a 76 PUCH (probably a '77 Model because it was built 10/24/76). I fiddled around about a month or so before I realized that "oldtimers" post is correct. To solve the problem, it just wouldn't pull me up the steep hills surrounding my town, I bought a biturbo and a 70cc kit. It now cruises fine (between 40-45 mph) and will pull my "bulk" (235lb) up the steep hills to the commuter train station 8 miles away. I haven't had any problems w/the conversion. However, it was not exaclty a cheap fix. You may want to try the biturbo route first.