Finding parts

[WINGNUT308]

Trying to repair 3 Bachmann 4-8-4 locos, mid to late '80's early 90's steamers.  They all have the 'pancake' style motors (white) and they are trashed.  Where can I locate 3 (or 4) of them, along with some replacement brushes and springs ??  At 75(yo), I'm kinda new at this stuff........  Any help is appreciated, Thank you.