$-4-0 #119 Union Pacific

[RkyGriz]

Hi guys. I recently bought a Bachmann #119 4-4-0 Union Pacific locomotive.The first problem is that, while it runs quite well, the front pilot will not stay on the track. I've tried to correct it but no go. The second issue with it is that the headlight doesn't work. I took the locomotive apart and decided to remove the headlight wire as it was causing some problems when I tried to reassemble the loco as it didn't seem to be going back together correctly. The final issue that I'm having is that a small, funny shaped copper spring fell out and I don't have a clue as to where it goes and the diagrams on the Bachmann website do not show where it goes.
Any help you can offer will be greatly appreciated !
Later,
Andrew.