I've had a lot of issues with the 2-8-4 N scale loco that I bought.  It seems to bind up and get hung up on the track.  Also the front is extremely light, so the front wheels hop off the track causing derailments.

I had one particularly bad derailment and when I picked it up the tender became unhooked.  I don't see anything in the included diagrams that show how the tender is supposed to be attached.  It has two copper prongs which I assume carry current.  It appears there is a slot in the post on the engine that these should fit in.  However every time I try to run the train now it shorts out.

Can someone explain how the tender is supposed to be attached to the engine?