The Bach-man is referring to the remote turnouts that require a separate dc power to operate, if you are using the DCC onboard decoder equipped one's then yes you will be able to operate them with the EZ Command. You will notice a slight surge when the turnout is thrown

depending on the size of your layout would determine how many but my rule of thumb is there is never too many.
I run feeders every 3 feet on a 16x30 layout

Bachmann's video ......

https://www.youtube.com/watch?v=Ru1UP-Ao2rA

So real looking. What are your plans for the ground. Most substations in my area have gravel.

jbrock I only suggested returning as no one but James has come up with a possible cause, Who knows there could be a casting imperfection that no one see's. How can you there is only pics of the victim and not the suspect.

Obsessive cleaning could be the culprit if at one time of cleaning it was not assembled correctly, not saying this is what happened but if something did not line up just right could have caused this.

I have only went with a full tear down for lubing if a problem was detected. Normal oiling with one drop of LaBelle's lube's keeps them going. It is a known fact Bachmann over lubes their loco's 90% of the time.

Starting with fresh loco's may be the way to go or not.

Still have the receipt? Sounds like a call to Bachmann to replace said loco's.
I am wondering is the other loco's Sound Value also?
How often have you cleaned and lubed in the past 2 1/2 years of ownership. Could be a defective loco and as James pointed out, may have a cracked gear.

Appears this may be your set correct?
http://shop.bachmanntrains.com/index.php?main_page=product_info&cPath=258_269_270&products_id=1805
I am guessing you have standard turnouts with the plastic frog. That loco should navigate those turnouts easily. I would check your trip pin (hanging hose under coupler) and make sure it is not hitting the frog causing it to derail. If it is then I would suggest a coupler height gauge and a pair of these to bend them up.
http://www.micromark.com/trip-pin-bending-plier-n-scale,7583.html
If you have a video camera you could place it at the turnout and watch in slow motion to see what is actually happening.
Keep us posted.

Great job again Jonathan!
You have seem to incorporate ground effect lighting also  .
There's a country song that has a saying "dashboard lights give off a romantic glow" which you have seem to have accomplished also, oops that song quote is way off. It was a cargo light. Anyway the dash lights look good also.

I believe the one you have is the older version. I have the DCC version which pretty much the shell removal is close to the same way.

DCC version pop of the fuel tank and by each truck there are tabs. I use toothpicks to help hod the shell apart as I spread the shell from the chassis. You don't have to remove the couplers but I do as not to damage them.

DC version is in this link. At the bottom of the page it is noted how to release the shell which appears to be the same method.
http://www.spookshow.net/loco/bachgp50.html

http://www.layoutvision.com/sitebuildercontent/sitebuilderfiles/bh_small_layouts_2015_slides_download.pdf
http://www.wymann.info/ShuntingPuzzles/sw-timesaver.html

Do you have something in particular you are wanting to design or are you just freelancing something?
I found ANYRAIL.COM was a big help in designing a layout. Trial offer free up to 50 pieces but about $50.00 for the whole thing.

Here's a few links for you to glance over...
https://www.google.com/search?q=ez+track+layout+pics&rlz=1C1NHXL_enUS704US704&espv=2&biw=1366&bih=638&tbm=isch&tbo=u&source=univ&sa=X&ved=0ahUKEwiw2JLV7sfRAhVoqlQKHfx_DPkQsAQIGQ
http://www.bachmanntrains.com/home-usa/board/index.php/topic,20416.0.html
http://www.bachmanntrains.com/home-usa/board/index.php/topic,25804.30.html

Go to one of WoundedBears posts and click on his pics at the bottom. He has a great looking coal mine, although you may have a modern one it still is worth the look. Google ho coal mine pics and there is more.

Yes that controller has the accessory prongs needed, just cut the end off the red plug and feed through the accessory plugs.

Research is good but if you answer the questions you may not have to research far.

Thanks James, have not been able to get back right away with work.
I have heard of a section of EZ track being dead before but I don't understand how since it is solid rail. I think it was on this forum I read that. I would do a continuity check on the piece in question.