ho f7/f9

[sooner49]

I have a issue with the drive train on f7/f9's  Recently two that I have started  to vibrate and are both very noisy, they sometimes will even not move.  I checked the drive trucks and all the gears are okay.  I checked the drive  shafts: one is a dual flywheel the other is a single.  Checking the shafts and they appear need to be replaced, okay I will order them from Bachmann, fine.  My problem though the coupling part inside the flywheels also show some wear, that could count for the noise  .  I have another 2 month f7 and you can barely  it running.Does anyone know to get them.  I have talked to Bachmann and they told me they are not avaliable.  Both of these are fairly recent produced.  Any ideas out there, it would be a shame, and expensive to have to replace them.

More info
both are dc.