Help putting puck mouse back together

[dos]

I took apart my puck mouse today for the first time to clean it as the movement was a bit rough. When I unscrewed the three bottom screws holding it together I didn't realize you're supposed to flip it around and open it from the top, and a few components inside aren't held down and just fell out: The white plastic guide wheel and spring, the M/T switch, the metal back plate that sits behind them, and another very small metal piece. I figured out how everything goes back together except for where the small metal piece goes, and no matter how I put it back together it now barely works in mouse mode, as if the guide wheel isn't putting adequate pressure on the ball to contact the X/Y rollers well. It works fine in trackball mode. I'm pretty sure the small metal part is the cause, I just have no idea where to put it. Can anyone help?

The metal piece:

[famiac]

Post a picture of the mouse internals. I remember this piece but i don’t have my mouse near me