I have a 1979 sears gt 16, powered by a one cyl. tecumseh that we have used for years for gardening. I am in need of help to figure out how to make it go again and stop slipping on the belts. At first I thought the varidrive was at fault. I replaced it with one known to be good, and no avail. I replaced the front belt that was badly cracked, no avail. I tried to take up slack in the rear belt but that didn't help me. The rear belt seems to almost always have slack. Someone said they don't usually stretch in length but I dont know for sure if that's true. As far as I can tell, I got 3 problems: 1. I do't know what the original belt lengths were. 2. I don't know with the varidrive if there is ever supposed to be slop in either of the 2 belts so I don't know how far to take up the adjustment. 3. Our garden isn't in yet and I don't know what to do. If you know anything about these, I sure would be thankful to you. John