I'm sure I could probably find this in the owners manual but I can't put my hands on it right now. Yesterday, while finishing my last mow I noticed the mower seemed to be bogging down a lot more than usual while using my BacVac. I mow w/ Peltors on so sometimes I don't hear rev changes etc. Then I realized that my throttle seemed to be backing down about 15% almost as soon as I increased it to max. It would back off and I'd push it back. Is there a tension adjustment or something to keep it "maxed"?