Loco shorting: Bachmann 9f

[philsandy]

Happy New Year everyone.

Had this loco a few years and it's now started shorting as soon as it's placed on the track.

It's not being caused by the wheels on the sprung axle (4th) contacting the chassis, (common problem apparently) I fixed this when I first got it.

I'm looking for suggestions to start the process of elimination, electrics is not my strong point.

I've tried a few things to try and find the cause ie. uncoupled the tender, unplugged the decoder, placed the loco on the track with front wheels only contacting the rails and then with rear wheels only contacting the rails, and it is still shorting.

Any suggestions please?

 

[DCB]

As replies seem somewhat sparse...  I don't have a Bachmann 9F but have had much hassle from various models, number one suspect is a wiper pickup touching the chassis any pickup on one side touching the wheel and another touching the chassis can cause this.   A swollen chassis from Mazak rot can exacerbate this.     Not sure if the Bachmann 9F has a layshaft but the Hornby Q1 has one and that works it's way out and fouls on a driving wheel shorting it out when it gets bored.  If the body has been off a wire can get squashed against the chassis and damage the insulation causing a short.     If all else fails take the loco apart (hopefully with a diagram of what fits where to rely on)  and if you can't fix it sell the bits separately on eBay.