Cleaning old 4-6-0 G scale wheels

[Rivercoon]

I have an old (1980s ?) 4-6-0 loco I'm trying to get running.  It needs a push to get started, starts and stops as it moves slowly, and shoots sparks from the front wheels.
I'm guessing the main problem is just dirty wheels.  There is no pitch or other signs it has ever been run outside.  Just lots of oxidation.
What is the best way to clean the wheels?

[Loco Bill Canelos]

Hi it could be that the front truck is shorting out.  Try turning it around.  The arrow on the front truck must be pointed forward!  Cleaning the wheels with a q tip dipped in solvent helps.  Could also be gearbox problem.  What is the road name on the loco and the cab number?

Loco Bill