I guess it would be the same either way but have you checked that the electrical connections are still attached to the motor? I've had a couple of things where over time the connections break away. Most seem to be attached with just a tiny blob of solder and I imagine all that shaking would knock it loose over time.
I haven't taken mine apart but I can't believe there is much to it inside other than a motor and some gears.
There are really only 4 things that could go wrong and 3 of them would be fairly simple fixes. 1 cord is not connected or has a break somewhere, 2 motor is bad, 3 switch is bad, 4 gears are jammed up and won't let the motor turn.
If you have a radio shack or similar electronics place you could probably get replacement parts to make it work again (motor or switch which ever is determined to be the problem). I think little electric motors like that are pretty bullet proof so that would be my last expected place for a problem, there just isn't much to them.
If you are not to handy with things like this I bet a decent RC or train shop would have someone that would be able to figure it out pretty quickly. If they stock plastic maybe you could bribe them, "you help me fix this, and I'll buy this nice big model kit from you".