HP Laser Jet Printer Pro - Tray 2 not picking up paper, white plastic gear wheel fell off

[k0m]

I discovered a white plastic wheel had fallen off and in Tray 2 when the printer broke down the other day.  I am not sure where this gear or wheel fell off from.  Been doing research for a week straight and I can't wrap my brain around where it belongs.  Anyone have / have had this issue before?  It's a small gear, an inch in diameter.  I tried to attach a picture but it won't load it.

[Repairatrooper · Accepted solution]

If you turn the paper tray over and look at the bottom, the gear seats there and it keeps the tray width slides aligned so that when you load paper the paper it is centered. 

[k0m]

Thank you!  I was able to place it there but there seems to be a bigger problem.  The printer is making all sorts of noise and there seems to be a jam in the rear print paper path.  I will do some more troubleshooting or post another question about it.