My husband and I are trying to reset the recoil on his 1970-something MW Sea King. We're not sure how to set the tension. The spring works as well as everything else. We've concluded that there needs to be tension before the string is pulled. How we are to do that ?? We've taken the pin out and tightened from the screw at the top but for some reason this does not work. By the time we get the pin back in we have lost the tension somehow.