Mercury Sable

You should alwasy give engine and car mileage when you make a post.

That buzzing sound is you tranmission or power steering pump they both make the same noise.

Once a transmission slips one time the bands are burnt. It will be a waste of time and money to change the fluid as it is already too late. Those trannys should be servcied at 40-50K miles and no later if not you will have the problem you are having now. You need an overhaul Good luck