I just bought a dcc set and everything is okay.  I have a problem that I s[ent many hours trying to fix.  I has a  dogbone shaped.  reverse loop on each end connected by a single track. My problem is this.  The loco enters either loop okay but when it enters the connecting track the engine doesn't just stall it slams to dead stop, I have to assume that it goes out of phase with the connecting track.  Without going to the expenses of buying expensive automatic reversing modules, is it possible to manually.  I have looked everywhere I can think of books, internet etc..  Can this be done if so how?  The layout was already completed when I wanted to use dcc. 
A[ pieces of information,  both ends of both loops are isolated on both ends of the loop  This is my first layout so I'm stumped.  Any help would be appreciated

I am having a track problem.  I have a switch that is driving you crazy.  It is doing what I want to call "splitting the switch."  With switch set to go left ( I physically check it )  the loco will go right.  the polarity of the track is correct,  in fact the right siding is dead ( turned off).  I can not get to go the left track.. Thanks for the help

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.