Asking around town a few people say they have had the same thing.  Seems like the older locos don't like the Bachmann E-Z Command DCC using channel 10.  If they are left on too long or you persist trying to get it to work the motor just burns out.  So I'll use this on my smaller layout using DC.
Thanks for the suggestions.
piblonko

Thanks Tylerf & Joe I did what you suggested & it works on DC but not on DCC. 

I have run a basic Bachmann E-Z COMMAND DCC unit with no problems on DCC or with analogue locos using channel 10.  I bought a second hand Bachmann Niagara 4-8-4 loco with steam & it runs intermittently & when it does its very jerky in action.  What would cause this, any ideas please?