Greetings,

   I'm new to this board but I can't find any information anywhere on this topic. I'm replacing and old 3-poler with a 5-pole motor in an older Bachmann SD40-2 (white box affair). The original 3-pole motor had a clear thin plastic dust cover (?) over the open-faced motor that I assume insulated it from the metal chassis. Well, I trashed it. Is this cover necessary for proper operation before I put the 5-pole in? Thanks guys-Marcel