How do you rewire cleanand Athearn locomotive?

The best thing to do is have a professional do it. Check with your local hobby the shops and see if they know a person well qualified to handle this?

HO RTR GP38-2, BNSF/Heritage #2094

$53.99

Athearn HO Scale Ready-to-Roll GP38-2 – BNSF/Heritage #2094…

HO 4-8-8-4 Big Boy/Weather, UP #4016

$277.18

The Union [...]