I love the 'Spam Cam' (Rebecca) , I doubt it will see the shop's as its manufactured in 00 - Hornby Bullied pacific ,

hi Brokemoto , the layout is a secondary line above my main layout and is 2 tracks on the level although one above the other , also I have the latest 4-4-0 Bachmann and to enable tight curves you need to trim the inside (cut in half) off the cylinders to enable the front truck to pivot the drive shaft do not need to be altered . again using the long EZ coupler on tender .
Also one 0-6-0 is Durango and Silverton set and other is pizza cutter wheels and both locos have center wheel flange removed with help from Unimat 3 lathe .

here you should see the 0-6-0 switcher and old timers on tight curves , use long couplers and slight trim to tender front/cab roof .


https://www.flickr.com/photos/seacote_lad/32701160833/in/dateposted-public/
https://www.flickr.com/photos/seacote_lad/33515871845/in/dateposted-public/

the 44 tonner with carefull modification will do tight curves - pull out the truck and care full trim the 'pip' that holds the truck to the chassis , trim each side to about half wide - then do other side of truck , now do second truck .
by doing this you will enable the trucks/loco to traverse more freely down to 12 inch diameter  (not radius  )
I tried posting photos yesterday but forum would not accept , I also have 2 x 0-6-0's that do same layout , I will try photos once more.

same happened to mine - shop new out of the box , Bachmann UK fitted a new decoder . under warranty .

last resort - although new could be split gears ?

most important of all white glue Elmer's/Woodland or other makes - dry's clear .

for analog (12 volt DC) to slow things down try a 12v bulb (not LED)  in series with one of the wires between the controller and track .

try a carpenters pin pusher used for panel and veneer pins , most tool shops should stock them , or internet shopping .
alternate method is to drill (pin vice) small hole through sleeper/tie and push track pin  through tie into cork bed .

the varnish type insulation on the copper wire may have worn off and shorted together , it happened to my Bachmann N&W 4-8-4 J class and fried the de-coder , after I painted the wires black and new de-coder it has been ok  , one day it will/may get re-wired ( )

could the fault be large flange wheel's (pizza cutter) , the good running loco may have finer scale wheel's ?
the larger flange causing the loco to lift ?

all Bachmann new rolling stock/cars (may be not train sets) are fitted with EZ magnetic couplers , if you can have a look to see how they should be fitted ?
some are held with a push pin and others with a tiny screw to the coupler box/mount.
I have fitted them to my 6 McKinley cars , also of note they work with Kato magnets - I have not tried Bachmann magnets.

try this - you may have to log/sign up the the forum ... (play nice   ).....

http://www.nscale.net/forums/content.php?63-Bachmann-0-6-0-Switcher-DCC-conversion-A-complete-how-too-(pic-heavy)

the contents are heavy with lots of images  

plas man

edit ... found the original page with photos including fitting of de-coder - its a good write up .

http://www.nscale.net/forums/showthread.php?20301-Bachmann-0-6-0-Switcher-DCC-conversion-A-complete-how-too-(pic-heavy)&p=182287#post182287

lets hope the colour match is as good as the heavy weight's , the Union Pacific livery is a good match for Kato's colour's , both makes run in a train and are undetected by the eye 

well I must have the duff one !!!
Bachmann UK couldn't fix , they returned saying within running tolerances , but admitted it needed new wheels and axle (none in stock and would not be getting supply's) , also returned with faulty valve gear to rear engine , another complain to the hobby shop sent it back , on return still within tolerances - but this time with bits of valve gear missing on opposite side front engine , needless to say now only purchase diesel loco's .

that apart it is a sweet running loco (apart from the wobble on mine) can crawl sleeper to sleeper (rail ties) as slow as 5/6 second's , can do 11'' (second radius) curves - not good on tight S curves , great haulage and silent running motor .