I am having a problem with my tention pulley on my Simplicity 1530 pacer 34 in cut. Mower belt has come off three times and have been able to get it back on using the lever to move the tention pulley. Now the tention pulley will move but now when I release the lever it goes slack and no tention. There is one spring, should there be two, what am I missing, got to be something simple. Just got it about two months ago, no manual.