Electrical problem with an old Hornby Jinty

[Ken Shabby]

This is early seventies Hornby Jinty chassis minus the smoke unit. I bought it very cheap, and it was a ten minute job to get it going again. Unfortunately I damaged the axle bushes while altering the back to back measurements.
This meant the chassis was shorting out.
I fitted new axle bushes this afternoon, and double checked
the chassis ran smoothly and that there was no problems with the quartering.
When I fitted the motor, it wouldn't run.
An entire afternoon was spent fiddling with it. I used the crocodile leads to test the motor which ran fine when not fitted to the chassis, also I doubled checked the chassis with a multimeter, and shunting it round the layout with another loco and it wasn't shorting out.
As you can see my method for wiring the motor to the pick ups is very basic, but this has worked fine on plenty of other Triang 0-6-0 chassis.
I'm out of ideas, and would be grateful for any advice.

Thanks,
Ken

[Mountain]

Peters Spares started having bushes for old Triang and Triang-Hornby wheels made for them so give them a try.

[aleopardstail]

if the motor runs off the chassis, the motor is fine, if the chassis rolls fine without the motor, the chassis is fine.

when I DCC fitted my J52 initially it hardly moved, it may be the motor worm is binding, try a bit of grease and without power rotate the motor bay hand when its installed (tooth pick or something with care) if it turns freely there is another issue.

with the motor out check the resistance of the coils between the terminals, refit and check resistance between the wheels, it should be roughly similar

further test is hook up multi-meter to measure current, will show if the motor is stalled

[Flashbang]

I think I would remove the bolt in the top of the motor (ensuring the magnet remains in place) and thoroughly clean the top of the motor and the Vee spring where the bolt secures it to the motor. The motor looks rusty in the fixing place for the vee spring and it might be a high resistance connection. Also clean the end of the bare side of the Vee spring finger where it connects to the brush as this also looks very dirty in the picture. If you're not replacing the brushes, also clean the inside face of the brush that the bare spring connects onto as It looks dirty. Also check that the soldered wire on the insulated brush isnt pulling that brush away from the Commutator causing loss of conatct with the Commutator

[Bigmet]

Don't need to do anything to the motor. The wipers are on the conducting wheels thus live to chassis, while the out of sight insulated wheels have no current collection; that's your problem

[Ken Shabby]

Problem solved, she's a runner.
Thank you all for your advice, especially Bigmet who spotted my school boy error.
Ken

[Bigmet]

Problem solved, she's a runner...

Good outcome, and you can have one guess at who has made the very same error!