fixing the recoil on a 70's ariens snowblower?

Used to work, but now when you pull the recoil, all I get is the back and forth pulling action. It does not turn the starter. I took the recoil off and tried to change the tension. After I put it back on it turned over about 2-3 times and then the recoil went slack again. Any ideas on how to get the correct tension or why it does not "catch" in starting the snowblower. Thanks