Took apart my TSU9400 - what is this part?

I followed jwatckins helpful directions for taking apart my spare TSU9400 hoping to figure out why the touch screen was not working (I did not succeed). When I put it back together I ended up with an extra part (I hate that) with no idea where it goes or what it does. The TSU94000 seems to [not] work as before. Can anyone tell me what this is and where it goes?

https://laoe.link/TSU9400part.png

David