This is not abnormal for Athearn locomotives with sintered iron wheels, it is not good for your track though. Many replace the iron Athearn wheelsets with nickel-silver ones NWSL, or another source.
A band-aid approach is the burni***he wheels with some 1000 (one thousand) grit emery paper, which will remove the non-conducting build up (the build up is rust, so solvents won’t do anything).
Wow, I’ve never heard of this problem before, and I run several Athearns, both original and Genesis. Maybe I haven’t been watching the wheels closely enough? I have read many comments about changing to North West Short Line wheels, but no one previously mentioned the sparking problem.
Thanks for moving your question over here, I didn’t mean to sound rude, but as you can see the answers are coming. This is the place for HO related questions.
And now my two cents. Back in the early days of command control, about 20 years ago, there was an article in one of the magazines, about using Wahl hair clipper oil. It seems that this oil is electrically conductive, and helps to reduce sparking by improving electrical contact between the wheel and the rail.
I have tried this, and it works, but at some cost. After a while, the oil collects dirt, and eventually a buildup of “crud” forms on the wheels of all the cars. This practice may have fallen out of use for that reason.
NWSL had just started making replacement wheel sets for Athearn back then, and they worked well. Prior to that, some of the people I knew actually had their wheel sets nickel plated. I’m with nfmisso on this, NWSL wheels will solve the problem.
Sadly the Athearn Blue box engines sparkle and twinkle as it goes down the track…This is as old as the sintered iron wheels that replaced the old brass wheel on the Athearn units.i am yet to change over to the NWSL wheel sets…I simply use my Dremel tool on the slowest speed and shine those wheels up by turning those wheels by hand…
This is not the job for the newbie or those that are faith of heart but for experience modelers…Above all if you try this be sure to be very careful.