I have a Ford AOD that probably should not have been rebuilt due to too much debris in the trans and is making a buzzing noise that I think is coming from the valve body,the reason I think its debris caught in the valve body is I can feel it in the shifter and when I shift the noise changes. Changed the fluid and it was quiet for a week but works fine so is there anything I can add to the fluid that can dislodge the debris or would one of those trans flushing machines do the job.