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

Steve
November 2009