I have two of these On30 Diesels, lovely models, heavy as bricks and originally both were very smooth runners.  Since then I have fitted sound cards to both, one of them runs beautifully, somewhere along the way with the other one, one of the bogies/trucks has decided not to pick up power, which makes the loco stoppy/starty, ditto the sound card.

I have run a multimeter over it, and it seems that the pickup(s) might be faulty on that bogie, but I have no idea really.

So my question is, are there instructions which would tell me how to access the springy thingies directly to check that they are contacting the wheels properly and/or remove the bogie to enable its replacement ?  I have the exploded parts diagram, but it doesn't really help in this respect.

I otherwise have no problem with removing the body shell to access the innards, but not the bogie.