Spectrum 4-4-0 wiring to loco

[JNLRET1]

I have a Spectrum 4-4-0 loco.  One of the wires coming from the cab caught on something and tore out.  I want to be able to get inside the chassis and resolder this wire and try to shorten the others (they're way to long).

It looks pretty complicated.

Any suggestions?

Thanks