4-8-4 wobbles

[curt F]

my 4-8-4 wobbles or rocks from side to side as it goes down the track after I did a stupid thing. i took the cover off the drive wheels to oil and the engine fell over and wheels fell out. how does all of these things line up to stop the rocking from side to side

[Hunt]

Research quartering wheels steam locomotive for something you understand.  Quartering wheels not as hard as you may think after first reading or viewing a how to video.   A wheel quartering jig helps a lot if you are mechanically challenged. 

There is always Bachmann Service or local repair person.