cannot solve derailment problems

[rrmchone]

i have been workin around the layout for a while just fired it up for the first time in a few months after construction but seems to be a derailment issue   when running six axel engines i  need some help trying to figure this out.

[bobwrgt]

What locomotive?  Just one?? What brand? HO scale?
Does it happen in just one place or all over?? On the straight or curve??
What radius track?? Are the wheels in gauge and do you have a track gauge?
Are the coupler pins hanging to low??
Need information.

Bob