Question Bach-man on a Percy model

[Diesel #261]

Mr. the Bach-man
I barrowed a Percy model from a friend on Sunday to run at a model show for the kids.  As I was running him he just stopped.  The motor wasn't hot or smelled like anything a motor shouldn't and all his wires were in place.  I also checked his wheels because some of the people at the show don't clean the wheels on their big trains before they run them.  His wheels were clean and shinnie.  I tried pushing him along and tapping on him but it did no good.  I need to know what the problem is so I can fix it before I return him.  Please help.

[the Bach-man]

Dear Justin,
It's difficult to tell without actually seeing the loco. Try having your local hobby shop look it over.
Good luck!
the Bach-man

[Michael]

Could be this:
-Wire came loose
-Side Rod jammed
-His little copper contact(behind wheels) are ditry or bent away.