Jerky Mogul

[Old Steamer]

I recently purchased a Bachmann standard line 2-6-0.  It ran well for several months.  But the mogul sit idle for a couple of weeks and now it is very jerky.  In truth, it was always jerky in reverse.  But forward running, it was very smooth unless is was cold in the hobby room.  But it was warm and running smooth in a couple of laps.  I have a figure eight layout.  Even now the engine runs fairly smooth uphill.  But when going downgrade, it jerks terribly. I have given it plenty of time to warm up.  And the position on the track isn't consistent.  I have cleaned the wheels and the track.  Neither have made a difference.  I have noticed that if I hold the mogul in place with my hand, it runs very smooth.  It seems when it is under a load, either going uphill or held in place, it runs smooth.  But when there is little or no significant resistance, it is jerky.  Speed is a factor too.  it runs more smooth at slower speeds.  But when I crank up the throttle, the jerkiness worsens.  What is going on here?  Does it need lubricating?  Is there a gear or motor issue? I have no reservations opening it up if needed.

And where are the pickups?  I cannot find any pickups on the wheels.  Are these inside what I would call the gearbox?

I apologize in advance for my ignorance,

Old Steamer

[rogertra]

Unless you are comfortable with taking a steam engine apart and servicing and or repairing the model, I strongly suggest you return it to Bachmann for service.   

[Doneldon]

Steamie-

It sounds to me like you have some kind of slop in your drive system. That could mean a cracked gear, loose motor mount or a few other things. As Roger mentioned, this might not be an easy diagnosis and fix for someone who is new to the hobby. His advice about returning it to Bachmann is sound. They will fix or replace your loco for free if you can prove you purchased it within the last year. Otherwise it will cost $25. That's a reasonable price to avoid the headache and risk of a self fix.
                                                                                                                                                                    -- D