Replacing Lionel smoke unit fan motor

I want to replace the fan motor in my Lionel PWC 773 Hudson ( 38096 ) --- the set came out around 2005 / 2006

The motor runs but very inconsistent --- sometimes slow / sometimes strong / sometimes not at all

I've had it apart numerous times making sure there was nothing in the way etc

Alex M installed a super-chuffer and the engine runs great

My question --- What is the part number or just call Lionel and order a "generic" fan motor

Thanks in advance

Joe S