the computer was new. I removed the screw and dust, and put three small pieces of Velcro (just the fuzzy side) on the battery so that the back case would hold it in place, since the three ridiculous tri-screws were not doing anything, anyway. And put it back together.
And now, it works very, very well!
Somehow, I think an Apple genius would have not told me about having a screw loose...
Very useful. I was having problems with my trackpad, the cursor was jumping around irratically, and I figured the problem was likely to be either swelling of the battery that I could not see, or dust and dirt on the trackpad. I was at the end of my patience, and my warranty has expired anyway, so this time I VIOLATED APPLES' IMPERITIVE and took out the stupid battery. Piece of cake.
Two things I found, 1) the plastic tabs that hold down the battery were all three broken; the screws had been over tightened from the factory. There were small pieces of plastic from it under the battery on the trackpad. When I got the battery out, I found a very tiny screw loose on the trackpad. I have no idea where it came from, I suspect someone dropped it when this unit was put together, since this has been an on- again off- again problem since