Hi.
Just a suggestion.
You might try a pre-wired SMD in warm white for the headlight.
Here's a link to the one I did on one of my 4-6-0's:
https://www.youtube.com/watch?v=oi1tmLr-xZA&t=8s
You can purchase them here:
https://hdamodelworx.com/5-PACK-0603-SMD-WARM-WHITE-Pre-Wired-with-soldered-on-LEAD-WIRES-AND-RESISTOR_p_98.html
Or from other retailers who offer this type of SMD light.
They come prewired with resistors.
Mike

Hi.
I haven't seen the replacement gear boxes available for quite a while now.
Your best bet would be to replace the entire chassis with either a brand new one from the Bachmann parts store ($153.50 + tax and shipping).
 https://estore.bachmanntrains.com/index.php?main_page=product_info&cPath=69_671_669&products_id=12182

If you want to power your cars via track power, you'll have to get inside of them and do some very simple, easy wiring connections.
It's not hard.
In fact, it's a very simple and easy process.
If you're not willing to do the simple work, then don't.
Stick to the 9v batteries.
I don't have time to walk you through what is a simple, and fairly easy project.
I've done over a dozen of these Bachmann cars.
And several from other manufacturers that I can't name here.
Do you think that I knew how to do the job from the get go ?
No.
I disassembled the cars and figured it out on my own.
I even figured out how to change the original incandescent bulbs out for  5MM Warm White LED's.
I added capacitors and bridge rectifiers so that the lights don't flicker(what the capacitor is needed for),and bridge rectifiers(for the polarity change) so that the lights stay on when the cars are going both forwards as well as reverse.
LED's only work when the current is flowing in a forward direction.
And that's what you need to do.
Here's a video showing some of my lighting work
Note that every car on both trains has had track powered lighting added by yours truly:
https://www.youtube.com/watch?v=WIVpc0aSktc&t=11s
Good luck!

You have to purchase the wipers on the Bachmann parts store website.
You'll need two sets of these per car :
https://estore.bachmanntrains.com/index.php?main_page=product_info&cPath=69_75&products_id=649Of
 iI your car doesn't have metal wheels on the trucks, you'll need to buy two of these per car:
https://estore.bachmanntrains.com/index.php?main_page=product_info&cPath=69_75&products_id=581
And then you'll have to disassemble the cars to run the wires.
Mike

Unfortunately, that's a very common practice on Ebay.
Sellers think that they can make more money by selling the loco and tender separately.
And this is exactly what that seller is doing.
Grrr!
Well, at least he's not trying to pass it off as a V7...

Hi.
No, I didn't buy it, Bill.
I was tempted, but in the end, I decided not to get it.
I have a couple of projects in the works, and I already have a Christmas train(North Star Express Anniversary Edition).
I did like it,even with the mods!
Mike

Well, someone bought it.
Maybe it's a member of our little board?
If it was one of you guys, please respond with details after you receive the loco.
Thanks!
Mike

Hi, Bill!
He's still asking $415.00 plus shipping.
When did you see it at $370.00?
It's been on my Ebay watch list well before it became a conversation piece here.
It sure is pretty!
I check Ebay listings every day for Big Hauler parts as I'm currently looking for another D&RGW or D&S tender tank in the bumblebee paint scheme.
Best regards,
Mike

I think that this has had its' chassis swapped for an older generation chassis.
The valve gear is different from what is shown in the photo shown on the Bachmann website.
Also, its hard tell, but the front pilot looks like the old design.
Finally, the model number shown on the pictured box,91805, corresponds to the description on the Bachmann website as well.
Just my 2 cents here, but I think that this one is a cheat.
Perhaps not intentionally by the seller...
But it does appear that someone changed that Version #7 chassis for a version #5.
Mike

As I remember, there is only a small circuit board that is located in the back of the locomotive chassis.
It has two wires running from it to the sound drum on the front wheel axle.
The sound drum has a couple of metal strips built into it.
As this drum rotates on the front axle, these metal strips make contact with two metal contacts that are mounted inside the chassis.
There are two wires that (one red, one black) that run back to the small circuit board at the rear of the chassis.
This board has either one two prong plug for the tender sound (Standard Edition),or 2 two prong plugs(Anniversary Edition for the sound and rear light. Coal burners only ,as the wood burning Anniversary Edition models models usually don't come with a rear headlight. At least as far as I know, and I currently own 18 4-6-0 Big Haulers).
Bachmann calls their sound board in the tender a PCB.
If you click on the link for the tender flat on their parts department website, you'll see what I mean.
Therefore, that's what I am calling it as a common referent point.
The Big Hauler is a fairly simple locomotive to work on.
I have rebuilt at least 2 of the Anniversary chassis from the ground up using either new parts from Bachmann, or Ebay.
Matter of fact, I just bought and restored a #177 Denver & Rio Grande V4 locomotive.
I usually replace the older chassis on these with the newer Anniversary chassis, but this one runs very quietly, and is a strong puller.
So far, anyway.
I have a spare Anniversary chassis sitting in my closet right now, so I can pull it out and post some pictures of the working innards if you'd like.
It is a version 5.
As I understand it, the V6 does have a large circuit a board installed in the  the front .but the V5 does not.
Of course, I haven't had an excuse to open up my one V6 4-6-0...at least not yet...
Later!
Mike

For reference about the part of this discussion about a Bachmann PnP board in the 4-6-0:
Only the newest version,which is version number 7, has a Pnp board installed in the tender.
I own,and have totally rebuilt, versions of the 4-6-0 from V2 to V7,and the V7 is the only one so far that has ever come with a factory installed PnP board from Bachmann.
The electronic sound system that was included in all versions from V1 to V6 is referred to by Bachmann as the PCB board.
https://estore.bachmanntrains.com/index.php?main_page=product_info&cPath=69_671_669&products_id=5290
This should dis-spell any further references to there being a PnP board in the earlier 4-6-0.
Thank you !

Hi!
You may be money ahead to bid on this exact same item on Ebay:
https://www.ebay.com/itm/306199485982?
It looks good.
And it's currently at a great price!
Mike

Hi!
Did you perform a hard wire install by removing the original DCC system,then installing your own DCC controller?
Or did you install the new decoder using the Bachmann motherboard already installed in the tender?
If you did the second type of installation, did you try re-installing the original factory decoder?
I am assuming that you've already checked for loose wires,etc.
Other than that, getting to the motor will involve a complete teardown of the locomotive.
I've taken apart and rebuilt three (3) of the non DCC 2-6-0's, and it's not too hard.
You c\might consider seeing if you can send it back to Bachmann under the warranty if it's less than a year old.
Good luck!
Mike

Recently, I had a subscriber ask the following question on one of the videos on my youtube channel that features the ET&WNC #14 4-6-0 with factory installed DCC and sound.
He asked"Why is the chug(I'm sure he meant "chuff") rate so off for factory installed sound?"
I honestly don't know the answer to that, and I've never messed with the settings for this loco on my NCE Powercab controller.
I was just wondering if someone has a better answer than mine, which is currently going to be "Because they made it that way."
Thanks!
Mike

I'd really like to see Bachmann bring back the good old 4-6-0 in On30 scale.
They're great runners, and real beauties!
And maybe a few cars lettered for ET&WNC?
Ha ha!
Mike