My mower did not have the power it should have. I loosened and tighten a 3/8 nut connected to the throttle lever and since I did that the mower runs in high throttle and will not adjust down. The springs are attached and not broken. Since this problem I removed the engine cover and saw that a rodent had eaten the spark plug cable through. I put a new cable on, so that must have been the power problem, but now I have a high throttle problem. HELP!